Realistic armor penalties?

[Biggus]

This thread (https://forums.giantitp.com/showthread.php?624133-Nerf-mithral-armor&p=24851183) got me wondering whether the movement penalties (maximum Dex bonus, armor check penalty, and speed reduction) associated with armor in D&D were too harsh, and doing a bit of reading (and watching some videos like the ones here (https://www.benjaminrose.com/post/mobility-in-medieval-plate-armor/)) suggest that they are.

Given that apart from Clerics it's almost exclusively tier 3 to 5 classes who wear heavier armor, it seems to me that improving it would help game balance rather than worsen it.

So, I'm inclined to reduce the penalties for wearing medium and heavy armor. I'd be interested to hear people's opinions of what more realistic penalties for them would be.

[gijoemike]

Masterwork armor made from certain materials can pretty much negate all but the worst Armor check penalties. I am going to ignore shields for this. Splint and half-plate have the worst check penalties at -7. That alone tells you something because being completely encased in armor with plate mail that 2 other people have to help you put on is only an ACP of -6. We should consider lowering the ACP to only be -6. Full plate is the gold standard we look at when we discuss heavy armor. Note: A darkwood shield has its ACP lessened by 2. Called out special. That is the entire ACP for all non-tower shields. But we will look at the lamest armor in the game for this exercise.

Half Plate is -7 ACP and a max dex of 0.
So Masterwork Half Plate is -6 ACP; max dex of 0
Adamantine Masterwork Half Plate is -5 with max dex of 0.
Mithral Masterwork Half Plate is -3 (but that includes the Mstwk -1) as Mithral reduces the ACP by 2 more pts. (And adds a max dex cap of +2)


There is a unique way to make armor to reduce it further. HELLFORGED is an armor template that will reduce it by another +1. This comes from the DMG II. Hellforged Mithral Half Plate is only -3 ACP with a +2 dex. Hellforged is about an extra 1500 gp, iirc. A devil has to make your armor.

There is an armor enchantment (+1) that reduces ACP by 2 called Nimbleness from the Magic Item Compendium. Raises the Max dex by 1.

This leaves us with Hellforged Mithral Half-Plate of Nimbleness with a -1 ACP. We are SO CLOSE. Also this enchant raises the max dex by 1.

The gray dwarfs of Faruen according to the book races of Faerun have perfected an armor lubricate that costs 40g and takes 1 minute to apply to metal armor. It then lasts 1d4 hours and reduces the ACP by 1 point.

Properly Lubricated +1 Hellforged Mithral Half-Plate Armor of Nimbleness as a -0 ACP and thus no characters suffers any lack of proficiency penalty. Also, the max dex is +3. The total cost of 15590 + masterwork halfplate. So for 13k gp Armor check penalties aren't a real thing.


Given the above technique, a dwarven rogue can put this mess on and be 100% fine as they ignore the speed reduction of armor. They don't need to spend a feat on armor prof at all. That seems absurd but that is the rules. Any character wearing boots of striding and springing cancels the movement reduction.


So, what should be do to lessen the impact heavy armor drawbacks have on non casters? My suggestion is to get rid of them completely and make the proficiency required to wear it. Adjust the dwarven racial to actually matter.

[hamishspence]

Adamantine armour's reduced ACP is because it's always masterwork:

https://www.d20srd.org/srd/specialMaterials.htm#adamantine
Adamantine is so costly that weapons and armor made from it are always of masterwork quality; the masterwork cost is included in the prices given below. Thus, adamantine weapons and ammunition have a +1 enhancement bonus on attack rolls, and the armor check penalty of adamantine armor is lessened by 1 compared to ordinary armor of its type.

So it's ACP -6, same as "non-adamantine, Masterwork, half-plate".


Mithril items are always Masterwork, and the masterwork 1 pt ACP modification is included in the Mithril 3 point modification, so Mithril half-plate will be ACP -4.

https://www.d20srd.org/srd/specialMaterials.htm#mithral

Spell failure chances for armors and shields made from mithral are decreased by 10%, maximum Dexterity bonus is increased by 2, and armor check penalties are lessened by 3 (to a minimum of 0).

An item made from mithral weighs half as much as the same item made from other metals. In the case of weapons, this lighter weight does not change a weapon’s size category or the ease with which it can be wielded (whether it is light, one-handed, or two-handed). Items not primarily of metal are not meaningfully affected by being partially made of mithral. (A longsword can be a mithral weapon, while a scythe cannot be.)

Weapons or armors fashioned from mithral are always masterwork items as well; the masterwork cost is included in the prices given below.

[Silly Name]

There are a few ways to go around this:

1. Armor Class Penalties: yes, armor can be awkward and encumbering, especially if you're not used to it. You theoretically can do a lot of things while armored (https://www.youtube.com/watch?v=qzTwBQniLSc), especially if it's well-made, but you will obviously tire faster and require a lot of training to do all this stuff.

So, ACPs aren't completely unrequited, but since armor also has a max Dex bonus, they're actually far more severe when it comes to Dex-based skills. I'd suggest reducing the ACP for Medium and Heavy armors thus:

Hide: -2
Scale mail: -3
Chainmail: -4
Breastplate: -3

Splint mail: -5
Banded mail: -4
Half-plate: -5
Full plate: -4

It doesn't completely negate the existence of the difficulty of mobility in armor, but it means it's a bit less severe, especially when coupled with Masterwork and light materials.

2. Maximum Dex bonus: in the same vein as above, it is far too extreme. Up the maximum Dex bonus of all heavy armors by 1 or 2 points.

3. Movement speed penalty: ditch it. At best, keep the rule that you can only run at 3x instead of 4x in heavy armor.

Rework dwarf racial ability accordingly: you could give them the portions of the Endurance feat pertaining to armor, for example, and/or the possibility to ignore the reduced running rate.

[Dusk Raven]

As others have noted, real-life armor is not as burdensome as 3.5's rules would have you believe. Armor doesn't reduce your speed or agility that much, it just tires you out faster, which will generally just be relevant during overland travel. After all, if you're going long distances cross-country, armor is just dead weight until you actually get into a fight. In The Lord of the Rings, the Fellowship only has two mail shirts between them. One is worn by a dwarf, and the other weighs almost nothing. Everyone else goes unarmored. That being said, they live in a world without random encounters, and they cross the better part of a continent while only getting into a handful of fights that weren't expected. Also, your average DM is unlikely to care about such logistical details, and I wouldn't blame them. And PCs can just get a pack mule or a wagon to eliminate that issue.

In addition, there is one often overlooked aspect of heavy armor that you may or may not want to make rules for - it makes falls a lot more punishing. All that extra weight on you means your ankles will suffer a lot more. I found this out while doing research into why one might choose to go unarmored (for "swashbuckler" style characters), and I read an account by a veteran who said he'd known guys who took a four-foot drop, and wound up discharged for medical. Granted, "discharged for medical is better than dead," and by and large you'll be glad for the armor, but it removes a few of your options for maneuvering. You can't just drop off the roof of a building onto the ground, for instance, if you're in full body armor.

[Rijan_Sai]

So, ACPs aren't completely unrequited, but since armor also has a max Dex bonus, they're actually far more severe when it comes to Dex-based skills.

Just so we’re clear on this point, armor Max Dex Bonus does not touch Dex-based skills (that is what the ACP represents):

Maximum Dex Bonus
This number is the maximum Dexterity bonus to AC that this type of armor allows. Heavier armors limit mobility, reducing the wearer’s ability to dodge blows. This restriction doesn’t affect any other Dexterity-related abilities.
It is only the Dex-to-AC that is affected by the MD bonus.

[Biggus]

There are a few ways to go around this:

1. Armor Class Penalties: yes, armor can be awkward and encumbering, especially if you're not used to it. You theoretically can do a lot of things while armored (https://www.youtube.com/watch?v=qzTwBQniLSc), especially if it's well-made, but you will obviously tire faster and require a lot of training to do all this stuff.

So, ACPs aren't completely unrequited, but since armor also has a max Dex bonus, they're actually far more severe when it comes to Dex-based skills. I'd suggest reducing the ACP for Medium and Heavy armors thus:

Hide: -2
Scale mail: -3
Chainmail: -4
Breastplate: -3

Splint mail: -5
Banded mail: -4
Half-plate: -5
Full plate: -4

It doesn't completely negate the existence of the difficulty of mobility in armor, but it means it's a bit less severe, especially when coupled with Masterwork and light materials.

2. Maximum Dex bonus: in the same vein as above, it is far too extreme. Up the maximum Dex bonus of all heavy armors by 1 or 2 points.

3. Movement speed penalty: ditch it. At best, keep the rule that you can only run at 3x instead of 4x in heavy armor.

Rework dwarf racial ability accordingly: you could give them the portions of the Endurance feat pertaining to armor, for example, and/or the possibility to ignore the reduced running rate.

Thank you, yes I was thinking roughly along these lines. Good point about needing to give the dwarves something, I hadn't thought of that.


Armor doesn't reduce your speed or agility that much, it just tires you out faster, which will generally just be relevant during overland travel.

Yes, one of the articles I read said you'd get tired after a minute or so of heavy exertion in full plate, but since very few fights in D&D last that long, it didn't seem worth worrying about.


In addition, there is one often overlooked aspect of heavy armor that you may or may not want to make rules for - it makes falls a lot more punishing. All that extra weight on you means your ankles will suffer a lot more. I found this out while doing research into why one might choose to go unarmored (for "swashbuckler" style characters), and I read an account by a veteran who said he'd known guys who took a four-foot drop, and wound up discharged for medical. Granted, "discharged for medical is better than dead," and by and large you'll be glad for the armor, but it removes a few of your options for maneuvering. You can't just drop off the roof of a building onto the ground, for instance, if you're in full body armor.

I didn't know that, but it makes sense.

[Darg]

You get tired much faster from even the added thickness and heat retention, not just the weight. I used to wrestle and would sometimes wrestle in a padded jacket and thicker pants. While my mobility wasn't that affected, going even 2 minutes straight could be quite difficult. As a comparison, going just as hard in a shirt and shorts I'd get as exhausted in about 5 minutes. I can definitely see adding an extra 50 pounds would tire someone out quickly. You also wouldn't run as quickly because of the weight. So the run penalty is definitely accurate.

Now as for the move penalty I can see maybe negating it for a number of rounds equal to half your constitution modifier per encounter (minimum 1 unless your constitution is less than 10) to a total of twice your constitution modifier per day. These rounds not needing to be concurrent nor are they actually consumed unless you move above what the penalty allows. You can go beyond this number of rounds per encounter, but you become fatigued until the encounter ends. When this fatigue causes or is one of only two sources of fatigue that causes your character to be exhausted, the exhaustion ends at the end of the encounter. The endurance feat can double the per encounter and per day aspects. Toughness as a feat increases the number of rounds as if your constitution modifier were one higher and halves the penalties of fatigue and exhaustion caused by this action.

The AC penalty isn't all that bad. Between taking 10/20, aid another, and synergy you should be able to function. Shield AC penalty is only a problem while equipped.

[Elkad]

I houseruled out the speed penalties for armor. If you can carry the weight, that's all that matters. Triple instead of Quad for Run remains.
Max Dex bonuses are raised across the board.



In addition, there is one often overlooked aspect of heavy armor that you may or may not want to make rules for - it makes falls a lot more punishing. All that extra weight on you means your ankles will suffer a lot more. I found this out while doing research into why one might choose to go unarmored (for "swashbuckler" style characters), and I read an account by a veteran who said he'd known guys who took a four-foot drop, and wound up discharged for medical. Granted, "discharged for medical is better than dead," and by and large you'll be glad for the armor, but it removes a few of your options for maneuvering. You can't just drop off the roof of a building onto the ground, for instance, if you're in full body armor.

I jumped out of a lot of planes in the military, and landed in some tough terrain with a lot of weight. Sometimes my whole body weight in gear if I didn't get it lowered. A T10B drops you at 20-24ft/s, equivalent to a 7-9' fall, plus crosswinds (and you can't change your facing under a regular military chute, so you might be going backwards at 15mph).

Not only did I not ruin my ankles, I don't know anyone that did. I can't even remember any bad sprains (from landings, we had them walking around in rough terrain with massive packs). One guy broke his femur, but that's because he hit a cow, then the ground, and then the cow fell on him - not from hitting the ground.

So while I think it's possible to injure yourself that way, it's by no means common if you are fit and experienced with your gear.

I've been out 30 years now, and weigh 50% more. I was on a low roof and my ladder blew down not long ago. Gutter, so no way to hang to reduce the drop. About 10' to a soft lawn. I stepped off, got up, put the ladder back up for the other guy with me. Had some bruising on my left buttock and side, but nothing major.

[Martin Greywolf]

As someone who wore armor, for long and short periods of time, for fighting and for trekking across a forested hills: you all don't have a very good idea of what armor is like.

First of all, the most egregious errors.

Armor and falling

Armor protects you hell of a lot from falling, whether it is gambeson or full plate. Seeing as you are able to afford armor, you also are able to afford a few martial arts lessons, and one of the first things you will learn is how to take a fall. There are several ways to mitigate fall damage, and armor helps with all but forward roll - which is rare to see outside of parkour shenanigans.

There is one area where armor can screw you over, and that is helmets. Depending on what kind you have and where it is fastened etc, a helmet can knock your head around in unpleasant ways, but what helmets do this is hardly consistent with their protectiveness against weapons - the worst helmets for this are ketle hats, for obvious reasons, to a point where some movie stuntmen refuse to fall with them on.

I managed to faceplant into a ditch, thorw a guy a dozen meters on a slope of a hill during a fight and get pulled down with him, have a ladder step break under me as I was climbing a wall with some pesky archers on it, took a swan dive off a meter and a half high podium for a bet and let me tell you, I never thought "wow, I wish I didn't have armor on to be safer in my falls". I did, however, occassionally slip on ice and smack by back onto the pavement and think "well, this would be nicer with a gambeson on".

Armor isn't that restrictive to dexterity

It can be, depending on what that dexterity means. Moving around in general and basic athletics aren't that restricted, but even something like drawing a bow or slinging may be. Again, some armor types are worse with this than others, full plate will restrict you very little (unless it is a tournament set for either jousting or melee), chain mail is probably the worst.

Fine motor control is often shot to hell, just dress in heavy winter clothes and go do something like sewing, with gloves on.

And again, a lot depends on armor specifics, a gambeson cut like a modern jacket will restrict you in unbelievable ways (to a point where you can't touch top of your head, or touch your arms above your head), but give it open armpits and bent elbows, and a lot of it disappears.

Armor only tires you faster

Well, yeah, this is the main thing. But listen, it's a major factor. It can kill you or send you to a hospital.

If you want to have an idea of what this is like, go do a sprint. Then put on your thickest winter gear and go do a sprint 10 times in a row, with short breaks, with your covid mask on. That's almost what it feels like to go and fight in fairly light armor (gambeson, mail coif with aventail and no helmet).

Helmets are heavy enough to give you a migraine after wearing it for 30 minutes if you aren't used to it. You can be a guy who does fighting regularly, put on a great helmet and then throw up after three matches of 1 minute each on account of restricted airflow. Gambeson alone rests on your chest a bit and makes breathing just a bit harder to do.

And all of this assumes reasonable temperatures. Do this in summer, and you have to watch your water intake like a hawk to no get dehydrated, and sometimes, even that won't help because you can get heatstroke in gambeson.

Let's also not forget that wearing armor alone tires you, without even fighting. Standing near a gate and guarding it in armor versus without are very different experiences, and the former is only preferable in freezing temperatures.

So yeah, this should be a major part of realistic armor rules. You can train to handle it, to a degree, but that's what proficiencies are for.

Armor doesn't slow you down

Well, not as much as some would like you to believe, but it still does, noticeably so. While the speed of your sword swing may be similar to non-armored, it really doesn't matter all that much, what does is your footwork speed, and armor not only makes you heavier, it also moves your centre of balance higher.

A lot about this depends on how armored your legs are - I most often wear padded hose with steel kneecap covers, and I definitely feel a penalty to my combat speed, especially when combined with abovementioned fatigue.

AC versus penalties is not consistent

I already mentione this, but here goes again. Penalties are inconsistent with how protective an armor is. Gambeson is all you need for heat exhaustion, and it doesn't matter much what else you put on top of it, until you start to use helmets with facial covering. Lamellar armor, chain mail and breastplate will do nothing to slow your legs down, or maybe they will, depending on what exactly, if anything, they do to protect your legs.

Just about the wrost type of armor is partial plate, where you wear full chainmail set and put breastplate and other steel bits over it. DnD doesn't really have this category. Next worst is chain mail, and full plate is right there at the bottom, being often better than a gambeson.

An aside: sure, you wear padding under amor, but there's a big difference between arming jacket that goes under full plate and a standalone gambeson.

Then you have stealth. Plate armor is noisy, unless it isn't because you backed the clanking plates with fabric or leather, then it is less noisy. Chain mail is prety much silent, as is gambeson, but if you try sneaking in them through a forest, and I did just that, you will quickly discover that you make more noise because you take up more space and bump into twigs.

Add to this the various magical materials, some of which should help with some of this, but not help with other bits at all, and you have a mess.

Why do you even bother?

I mean, DnD already has weird armor than doesn't really model even remotely how armor actually works and is centered around mechanical balance. Well, tries to be centered.

To make any attempt at realism, you'd need to overhaul damage and armor systems, and at that point, you may as well create your own game.

There is so much to fix here you are probably better off just rolling with it, or find another system.

[Silly Name]

Armor doesn't slow you down

Well, not as much as some would like you to believe, but it still does, noticeably so. While the speed of your sword swing may be similar to non-armored, it really doesn't matter all that much, what does is your footwork speed, and armor not only makes you heavier, it also moves your centre of balance higher.

A lot about this depends on how armored your legs are - I most often wear padded hose with steel kneecap covers, and I definitely feel a penalty to my combat speed, especially when combined with abovementioned fatigue.



Honestly, my main complaint is that D&D already has rules for carried weight and encumbrance affecting movement speed, so it seems more straightforward to defer to that rather than making you pick the worse penalties between weight and what your armor gives you, even if you have 40 in all your physical stats. Perhaps not super-realistic, but we can give martials some treats.


Why do you even bother?

I mean, DnD already has weird armor than doesn't really model even remotely how armor actually works and is centered around mechanical balance. Well, tries to be centered.

To make any attempt at realism, you'd need to overhaul damage and armor systems, and at that point, you may as well create your own game.

There is so much to fix here you are probably better off just rolling with it, or find another system.

I agree that the way D&D 3.X models damage and armor is far, far removed from reality, but in the interest of balance, or even just making wearing armor not an handicap, I don't think it's too much of a fool's errand to try to fiddle with the numbers a bit to make things better. The designers exaggerated things a lot, and ended up making armor usage a very bad option unless you invest a lot of money in negating all the penalties.

I'm not particularly worried about modelling stuff like heat, exhaustion and dehydration since the game already allows for 24h armor-wearing with no penalties regarding those things - to me it's an acceptable break from reality, and isn't particularly egregious considering all the stuff going on in D&D-world.

[Biggus]

Loads of stuff

Thank you for the expert knowledge, I will have a think about your points. However, in relation to your last point...



I agree that the way D&D 3.X models damage and armor is far, far removed from reality, but in the interest of balance, or even just making wearing armor not an handicap, I don't think it's too much of a fool's errand to try to fiddle with the numbers a bit to make things better. The designers exaggerated things a lot, and ended up making armor usage a very bad option unless you invest a lot of money in negating all the penalties.


...exactly this. I'm not trying to make armor perfectly realistic, that's impractical as you said. But the penalties for armor, especially heavy armor, seem excessive. I just want to improve it a bit in the interests of both realism and game balance.

[SquidFighter]

Having personnaly tried swimming with a chain-mail, I can attest for the realism of it's ACP on the swim skill.

Honestly, the only reason I was able to succesfully swim 25m is because, as a lifeguard, I was reasonnably skilled at swimming.

[MoiMagnus]

What I'm reading is that Armour penalty should be on Con checks instead of Dex checks.
Arguably, it should even be a Con penalty, the reduction in HP representing that your endurance is reduced.
In fact, if floating Con penalty did not get very weird, that's what I'd recommend. But with current rules, the possibility to go from negative HP to positive HP by removing your armour is too weird for my taste.

[Biggus]

Having personnaly tried swimming with a chain-mail, I can attest for the realism of it's ACP on the swim skill.

Honestly, the only reason I was able to succesfully swim 25m is because, as a lifeguard, I was reasonnably skilled at swimming.

Yeah, the double ACP for Swim was one of the things I wasn't going to change. One of the sites I looked at said tests had shown it's "possible, but very difficult" to swim in heavy armor.


What I'm reading is that Armour penalty should be on Con checks instead of Dex checks.
Arguably, it should even be a Con penalty, the reduction in HP representing that your endurance is reduced.
In fact, if floating Con penalty did not get very weird, that's what I'd recommend. But with current rules, the possibility to go from negative HP to positive HP by removing your armour is too weird for my taste.

Hmm, that's a good point, it does seem like it would affect the Con checks to keep performing strenuous activities more than the Dex checks.

[Martin Greywolf]

Honestly, my main complaint is that D&D already has rules for carried weight and encumbrance affecting movement speed, so it seems more straightforward to defer to that rather than making you pick the worse penalties between weight and what your armor gives you, even if you have 40 in all your physical stats. Perhaps not super-realistic, but we can give martials some treats.

I mean, if that carried weight ruleset was good, which I'm not sure about, it's close enough. Armor will probably hinder your total speed less than a carried load, but will be worse for fiddly little movements, but that's a pretty fine detail.



I'm not particularly worried about modelling stuff like heat, exhaustion and dehydration since the game already allows for 24h armor-wearing with no penalties regarding those things - to me it's an acceptable break from reality, and isn't particularly egregious considering all the stuff going on in D&D-world.

Problem is, then armor has almost no penalties, maybe a slight penalty to areas where you need very fine motor control, like playing a guitar with plate gauntlets on.

The problem here isn't that in doesn't hinder you, it's that outside of these two, the hindrance is arguably too small to be modelled accurately in DnD level of detail. I mean, you can shoot longbow in armor.

https://manuscriptminiatures.com/image/12637

https://manuscriptminiatures.com/image/23362

https://manuscriptminiatures.com/image/9813


Having personnaly tried swimming with a chain-mail, I can attest for the realism of it's ACP on the swim skill.

Honestly, the only reason I was able to succesfully swim 25m is because, as a lifeguard, I was reasonnably skilled at swimming.

Funnily enough, it's not the chain mail or plate that will get you in this case, it's the gambeson under them. The bastard soaks water like crazy - when I was washing my gambeson, clocking in at about 3-5 kilos, it went right up to estimated 30-40, enough that I had trouble lifting it.


What I'm reading is that Armour penalty should be on Con checks instead of Dex checks.
Arguably, it should even be a Con penalty, the reduction in HP representing that your endurance is reduced.
In fact, if floating Con penalty did not get very weird, that's what I'd recommend. But with current rules, the possibility to go from negative HP to positive HP by removing your armour is too weird for my taste.

Pretty much. Add to that a minimum con to be able to use armor, because let me tell you, first time I put on my great helmet ensemble (1kg crevelliere, 5kg mail coif, about 2kg of that directly on head and 4kg great helmet), I got about 7 kilos of weight directly on my neck that was only used to mail coif with kettle hat (about 3-4 kilos): I had to take it off after about 15 minutes and had a two-day migraine. It's not even heaviest helmet out there, some of them can go up to 10-12 kg (~8-10 kg directly on head), especially for tournament pieces.

And a smaller penalty to str mayy be in order as well, since you need to spend some of that strength on moving armor, rather than a sword. You are definitely a touch slower fully armored than without.

[Eladrinblade]

I always thought they aren't high enough. I notice a difference between shorts and jeans, athletics shoes and normal shoes, jacket on and jacket off. I can't get good range of motion in a winter outfit; there's no way a full suit of armor is going to be any better.

[SangoProduction]

I always thought they aren't high enough. I notice a difference between shorts and jeans, athletics shoes and normal shoes, jacket on and jacket off. I can't get good range of motion in a winter outfit; there's no way a full suit of armor is going to be any better.

As someone who's worn replica armor before (not properly fitted, but just...anyway), it's really not anywhere near taking something I could literally always do, and making it so I only have a 50/50 chance of succeeding.
Especially with articulated joints. Winter outfits just have a bunch of padding all around. It's meant to keep in heat, not allow for motion....something that's pretty handy to allow when its purpose is to keep you from dying when you need to swing a pointy stick.

[Saint-Just]

I always thought they aren't high enough. I notice a difference between shorts and jeans, athletics shoes and normal shoes, jacket on and jacket off. I can't get good range of motion in a winter outfit; there's no way a full suit of armor is going to be any better.

I've only worn chainmail (and one probably lighter than 95% of historical examples), but I have seen people do crazy things in full armour. I definitely think that it's incredibly easier to perform feats of athletics in armour than in cold weather outfits, at least if we are talking about things worn in sub -30 degrees.

In fact I am under impression that the easiest way you can emulate how armour hampers you, short of having an armour is to use wrist weights, ankle weights and I don't know a jacket with lots of pockets stuffed with shot? a chest harness with a few weights securely fastened to it?. It does slow your motions and causes more exertion but it does not limit your movements that much.

[Yak folklore]

There are also nonmagic augmentations that are applied to an item white it is being made masterwork, by increasing the masterwork dc, many are devoted to reducing this kind of thing. Keep in mind that in a world where every joe schmo wants to be the next Robilar, armor would be much more popular, inviting poor craftsmanship, IRL, only the rich bought armor, and it would all be masterwork with augmentations.
realmshelps.net/magic/magarmor-ability.shtml (the non magic ones have a *)

Also, people train to fight with armor, maybe make it a skill trick to reduce armor penalty.

[Martin Greywolf]

Again, been there, done that, talked with a ton of people who did the same with other periods, downloaded academical publications.

First off, forget replica armor unless you are absolutely sure it was made properly. If your chain mail has straight sleeves, it's bad, same for gambesons and so on. We're not even talking masterworks here, we're talking "this armor would be made in period only as an emergency measure by someone who had no idea how to make good armor" - an improvised armor, if you will. It was done at times, e.g. Battle of Gotland, but it was exception rather than a rule.

Armor limits your total performance in things like sprinting, running and so on a little bit, but if it is properly made, there are few things you literally can't do. What it does do is make your stamina drain like water out of an exploded dam. That's why you need to train armor fighting, and that's why even people who are trained sword fighters have, upon putting on a face-concealing (and therefore breathing restricting) helmet, promptly thrown up after two minutes of fighting.

And that... is not modelled at all by DnD. Because the way it should work is by giving people a level of exhaustion after N encounters, with armor making that N lower. And that would be in direct opposition to heroic armor-clad fantasy most people want when playing DnD.

[Darg]

Well, the positive is that you don't actually have to wear a helm to receive the AC bonus from plate. Although it can help vs rp actions. So breathing doesn't have to be too restricted. Honestly, an adventurer is very unlikely to be wearing a helm with a face plate anyway considering the loss of awareness and restricted breathing.

[liquidformat]

So what I am hearing is check penalty to lock picking, sleight of hand, disable device, perform (with wind and string instruments), and double on armor. Then from their dump max dex and insert fatigue rules for armor based on travel time while armored, length of fight while armored, and physical activities performed while armored. Maybe armor could have a some sort of fatigue bank based on the armor type and how many levels you have in a class with armor proficiency in said armor. The idea is performing tasks like every 10' you climb in armor takes a point, every mile you walk takes a point, every round of combat you fight takes a point, charging takes 2 points, and so forth and once you hit 1/4 your points you are fatigued and if you hit zero you are exhausted, if you hit -5 you are sickened. Something like that?

[Gavinfoxx]

You should look into Codex Martialis for better weapons and armor stats, in general.

Also, expert types, how would a cooling vest like in this article help things? And what might a magical version of it (or an armor enchantment, or an appropriately always cool special material, whatever) be?

https://www.thedailybeast.com/how-a-cooling-vest-invented-by-a-furry-made-its-way-into-the-us-military