In this thread, someone posted this:
Quote Originally Posted by noob View Post
I am definitively interested in seeing an adaptation of that system to 5e.
In light of that, I figured I might as well post the homebrew I've been working on for 5e weapons and armor.

Spoiler: Some notes of other things I'd be changing in addition to this

As I have been working on this for a particular campaign, there are other changes I'd be making. Some will impact some choices I made with the core of this weapon list, some won't.
The campaign itself has lots of prevalent magic, although most of it has a lower power level than I see in the existing magic items and spells.

If you have any comments about these non-weapon/armor changes, just put them in a spoiler tag, since I'll eventually make a separate thread for each of these, and don't really want to muck up this discussion with these other items.

Races: humans and half-elves removed. Darkvision replaced with Low-light vision. Potentially, all races have their stat bonuses changed to +2 to any stat and +1 to any other stat.

Feats: Removing Charger, Crossbow Expert, Defensive Duelist, Dual Wielder, Grappler, Great Weapon Master, Polearm Master, Savage Attacker, Sharpshooter, Shield Master, Tavern Brawler, Weapon Master. Most of these feats will be combined into a single feat and probably toned down (Crossbow Expert, Great Weapon Master, Polearm Master, Sharpshooter).
When I get this worked out a little more, I'll likely post that to a different thread and link to this one.

Crits: Crits no longer double the damage dice for an attack. Instead, they inflict extra effects based on the damage types of the attack. Crits would also apply to spells with saves. Crits would have 3 levels of severity, based on various features. Enemy mooks would have the weakest crits, while most PCs and elite enemies would have moderate crit effects, and legendary enemies and PCs who invested in crits would get the strongest effects. Crits would work with Legendary Resistance in some way, as well.
When I get this worked out a little more, I'll likely post that to a different thread and link to this one.

Saves: Saves imposed by enemies will be more evenly spread across all 6 stats. I will probably leave the existing spells PCs have access to as is (and not have enemies use them at all) in order to limit the number of changes players are expected to learn / remember. I don't *think* this will impact what saves each class provides, as each PC should suffer roughly the same number of effects targeting proficient saves as nonproficient ones (if we assume DEX/CON/WIS cover 75% of saves before while STR/INT/CHA covered the remaining 25%, the average character would have (75/3 + 25/3)% =33.33& of the saves they're forced to make be for proficient saves. In my system, each stat would cover 1/6 of all saves, and each character is proficient with 2 saves, so they'd still have 2 * 1/6 = 1/3 of all saves be for proficient saves.

Damage types, Resistances, Immunities: There will be no distinction made between magical and non-magical damage. A decent number of enemies will have resistance to one or multiple damage types. Very few things will resist bludgeoning, piercing, and slashing damage. Very, very few enemies will have immunity to any damage type.

Currency and generic consumable items: Rather than using gold as the currency, consumable items are used as the basis of it (inspiration for this came from the PC game Path of Exile, which is a Diablo clone that uses crafting items as currency both with NPC vendors and with other players). For example, healing potions will likely be one of the base items, which can be used to create/buy potions of Lesser and Greater Restoration (probably 5 and 25 healing potions, respectively), as well as potions of Raise Dead (probably something like 125 healing potions).
When I get this worked out a little more, I'll likely post that to a different thread and link it to this one.

Spoiler: Comparison to existing weapons

For the vast majority of cases, this list allows for all of the existing weapons to be created accurately. The main exception is with ranges for ranged weapons.

However, in some cases the existing weapon table is slightly out-of-whack. For instance, compare the Greatclub (1d8, 2-handed, 10 lbs) and the Quarterstaff (1d6 / 1d8 versatile, 4 lbs). Or a Handaxe (1d6, light, thrown) and Light hammer (1d4, light, thrown). Or spear and trident (identical stats, except the trident is a Martial weapon, costs more, and weighs more).

My weapon system works by taking a base category of weapon (light, versatile, or heavy for melee, and one-handed or two-handed for ranged), deciding whether it's a simple or martial weapon, and then applying some number of weapon modifications, which each impact the weapon's damage die.

The base damage type of each weapon is going to be either Bludgeoning, Piercing, or Slashing.
When I randomly generate ranged weapons, I roll three 1d3's, taking the highest value. 1=Slashing, 2=Bludgeoning, 3=Piercing.
If PCs are commissioning a weapon, I don't think it's necessary to impose any restrictions on what damage types they can select.

The scaling for weapon die is as follows: (Yes, there are a few points that have different progression than others, such as 1d12 -> 2d6, and I am open to suggestions about how to fix that without making that jump too big)
1 -> 1d4 -> 1d6 -> 1d8 -> 1d10 -> 1d12 -> 2d6 -> 2d8 -> 2d10 -> 2d12 -> 3d8 -> 3d10

In the tables below (which didn't format particularly well when I copied from my spreadsheet in excel), each +2/-2 adjusts the weapon damage die scaling by 1 level, and +4/-4 adjusts the weapon damage die scaling by 2 levels. (This was done because it simplified the formulas I'm using in excel when generating random weapons)

Cells with an n/a cannot be selected.
The 1-hand column for mods is used for Light or Versatile melee weapons, while the 2-hand column is used strictly for Heavy weapons.

For ranged weapons, the base range is determined by the following set of rules:
* One-handed weapons have a range of 30/120
* Simple two-handed weapons have a range of 80/320
* Martial two-handed weapons have a range of 100/400

When determining the final range of the weapon, add up all of the percentage values first, then increase the base range by that value. For instance, a Martial two-handed weapon with Setup and 2 Increased Range mods would have +200% range, which would set the base range to 300/1200.

The value of a weapon is doubled for each modification added. Some mods, such as Strong, count as 2 mods for the price. Ranged weapons cost twice as much as melee weapons.
When a PC wants to commission a weapon, the price is doubled.
(Note: I haven't decided what the base price should be for the stock equipment, and this is especially true for the base 5e gold-based economy which I am not using in my campaign. See spoilers above for more information about that)

1 hand 2 hand 1 hand 2 hand
Light 4 n/a 6 n/a
Versatile 6 8 8 10
Heavy n/a 10 n/a 12
finesse +0 n/a +0 n/a Can use DEX instead of STR. Cannot use with 2 hands
thrown +0 n/a +0 n/a Can throw (20/60)
reach n/a n/a -2 -2 can hit 10 ft away
mounted n/a n/a n/a 2 1-handed when mounted, disadv to hit at 5 ft. when unmounted
charged -2 -2 -2 -2 y Gain an extra elemental damage type in addition to existing damage types
strong 2 2 2 2 y Counts as 2 mods for price.
fancy y Looks exceptionally fancy, which will impact some NPC interactions
reliable -2 -2 -2 -2 Reroll 1's and 2's.
enhanced critical n/a n/a -4 -4 Weak -> Moderate -> Strong
weakened critical 2 2 2 2 Strong -> Moderate -> Weak
kinetic n/a -2 n/a -2 You may spend a bonus action to charge the weapon. The first time you hit with this weapon before the start of your next turn deals an additional die of damage.

1 hand 2 hand 1 hand 2 hand
4 n/a 6 n/a
Two-Handed n/a 6 n/a 8
setup n/a n/a n/a 4 Must spend action to set up or tear down. Cannot move weapon while set up. Cannot fire when not set up. Increases range by 100%.
loading 2 2 2 2 Maximum 1 shot / turn. (2 shots w/ rapidfire). Do not suffer disadvantage for firing while prone.
rapidfire n/a n/a -2 -2 BA: if you don't move this turn, make an additional attack.
entangling n/a -2 n/a -2 On hit: target's speed is reduced by 10 ft (minimum 5 ft) for 1 round.
charged -2 -2 -2 -2 y Gain an extra elemental damage type
strong 2 2 2 2 y Counts as 2 mods for price
fancy +0 +0 +0 +0 y Looks exceptionally fancy, which will impact some NPC interactions
improved range -2 -2 -2 -2 y Increases range by 50%
enhanced critical n/a n/a -4 -4 Weak -> Moderate -> Strong
weakened critical 2 2 2 2 Strong -> Moderate -> Weak
arcing n/a n/a -2 -2 Ignore interposing creatures when determining cover

Spoiler: Random sample weapons

weight training 1h dmg 2h dmg Range mods Dmg Type Price
Ranged One-Handed Martial 1 100/400 arcing, strong, enhanced critical Piercing 32
Melee Heavy Simple d8 kinetic, charged, weakened critical Slashing, Necrotic 8
Melee Heavy Simple d10 fancy Bludgeoning 2
Ranged Two-Handed Simple d4 80/320 entangling Bludgeoning 4
Ranged Two-Handed Martial d6 100/400 rapidfire Piercing 4
Ranged Two-Handed Martial d4 200/800 setup, entangling, enhanced critical, charged Piercing, Radiant 32
Ranged One-Handed Martial d4 100/400 rapidfire Piercing 4
Ranged Two-Handed Simple d6 80/320 Piercing 2
Melee Versatile Martial d8 d12 Bludgeoning 1
Melee Heavy Martial d12 charged, weakened critical Slashing, Lightning 4
Melee Versatile Martial 1 d4 reliable, enhanced critical Bludgeoning 4
Melee Heavy Martial d10 charged, kinetic, strong Piercing, Bludgeoning 16
Ranged One-Handed Simple d6 80/320 strong, fancy Bludgeoning 16
Melee Light Simple 1 charged Bludgeoning, Fire 2
Ranged One-Handed Martial 1 100/400 charged, charged, fancy Piercing, Acid, Force 16
Ranged One-Handed Martial d8 100/400 strong, Piercing 8
Melee Versatile Martial d4 d8 charged, reach, fancy, finesse Slashing, Fire 16
Melee Light Simple d6 strong Piercing 4
Melee Light Simple d4 Bludgeoning 1
Ranged Two-Handed Martial 1 150/600 charged, fancy, improved range, arcing Piercing, Bludgeoning 32

Armor works somewhat differently than weapons do, since I didn't want to penalize AC quite as much as I was willing to lower the weapon damage. Instead, armor modifications often modify AC by fractions of a point. When determining the actual AC provided by armor, add up the penalties and bonuses of the modifications and then round up.
No armor can have any combination of modifications that would reduce its AC below 10+DEX (or below 10 for heavy armor).

You can either use the existing armors in the PHB or the warforged armor scaling as the base for each armor type.

Light Medium Heavy multiple? Effect
-0.25 -0.5 -0.5 -0.5 y Gain resistance to 1 non-BPS damage type. Can be taken multiple times.
Immunity n/a -1.75 -1.5 -1.5 y Gain immunity to one non-BPS damage type. Can be taken multiple times.
Floating -0.25 -0.25 -0.5 -0.75 Take half falling damage, advantage to swimming checks, you always float in water.
Glowing -0.25 -0.25 -0.25 -0.25 Action: change between creating candle light, dim light in 30 ft, or bright light in 30 ft + dim light in 60 ft. Cannot extinguish light.
Sticky -0.25 -0.25 -0.5 -0.75 Advantage to checks where being sticky is helpful. Targets you grapple have disadvantage to escape.
Speedy -0.25 -0.5 -0.75 -1 1/turn when you dash, move an additional 30 ft.
Retaliatory -0.75 -1 -1 n/a For one round after you dodge, when missed by a melee attack, you may use a reaction to make an attack against the attacker.
Armor Effect -0.25 -0.5 -0.5 -0.5 Gain the listed Armor Effect for your armor.
Impeccable -0.25 -0.25 -0.25 -0.25 Never gets dirty or damaged.
Slippery -0.75 -0.5 -0.25 -0.25 Advantage to checks where being slippery is helpful. Advantage to escape a grapple.
Girding n/a 0.5 0.5 0.5 y Cannot raise AC above Base AC. Can be taken multiple times.
Snug n/a 1 1 1 Takes an hour to don or doff. Canít gain the effects of a Short or Long rest while worn.
fancy y Looks exceptionally fancy, which will impact some NPC interactions

Spoiler: Random sample armors

mods Price ac mod
Light Snug, Impeccable, Immunity, Girding, Girding, 64 0
Light Snug 4 0
Light Retaliatory 4 -1
Heavy Immunity, Resistance, Slippery, 16 -2
Medium Resistance 4 0
Clothes Impeccable, Floating, 4 0
Medium Impeccable, Immunity, 8 -1
Medium Immunity, Glowing, Girding, Resistance, Retaliatory, 64 -2
Light Glowing, Resistance, 8 0
Heavy Glowing, fancy, Impeccable, Snug, 32 0
Light Retaliatory, Snug, fancy, Sticky, Resistance, 64 0
Heavy Impeccable, Snug, 8 0
Light Slippery, Immunity, 8 -2
Clothes Retaliatory, 2 0

So, having put that out there, are there any suggestions for more weapon and armor mods that would be interesting (and less of a niche item than the Mounted mod, which I included mostly because it exists)?

How do you think this looks in terms of balance?