Materials for Weapons/Armor Advice

[Sere]

Hey. I was wondering if anyone with more knowledge or experience in medieval weapons would give some input on a setting I am building.

So I want to have some custom materials used largely for weapons and armor. (though if you wanted to give other info on their applicability for buildings or tools or such I am not opposed.) All of these materials will be non-magical, but I don't mind altering real life properties to make whatever custom material can be imagined, even at extremes. (For example if it is 1000x denser than lead that is fine, but if it crackles with lightning then it isn't.)

The problem is some of the practicalities of using weapons I don't have a great grasp on. If you could make a sword nearly weightless, like 0.1 grams, would that be good? What if you could make it (or parts of it weigh 25 Kg? Would another type of weapon like a spear or a mace change how much weight you would ideal want? How does hardness factor in? What about factors like yield, plasticity, malleability, fatigue strength etc?

I looked into all these properties from an online list, and while I understand them I'm curious how they would impact the quality of a weapon or piece of armor:
Density
Ductility / Malleability
Elasticity / Stiffness
Fracture Toughness
Hardness
Plasticity
Strength, Fatigue
Strength, Shear
Strength, Tensile
Strength, Yield
Toughness
Wear Resistance

What determines how sharp it can become or how well in can hold that sharpness? Is higher density bad or good or somewhere in between? What is most important for shattering? What other things would be good considerations that I am most definitely missing?

The materials are not necessarily limited to metals either, they could be stone, crystal, wood or basically anything as long as it isn't inherently magical. (Even if it greatly pushes the boundary on what these properties could be in our world.)

TLDR If you could design weapons and armor using materials with any mundane properties, what properties would be interesting to change and how would they impact the end product positively/negatively?

[Deepbluediver]

Weight is definitely an important consideration- think of something like an axe or mace. The weight, and where it's located, is what allows you put more force behind a swing (skallagrim has a good youtube video about this I think). Compare that to a sword which has more the weight along the blade and at the handle, which allows you to swing it more easily and adjust the direction of a stroke quicker (and also make it longer so it has more reach). In essence, weapons like maces and axes are more pure-offense, while a sword is a kind of offense/defense hybrid (and a shield would be nearly pure defense.
The best pop-culture example I can think of for a nearly-weightless weapon would probably be a lightsaber, but it's been pointed out that while they are kinda-used like a broadsword in the movies, it would probably FEEL a lot more like a fencing rapier.

In the real world, usually when you get lighter you start to trade off strength, although there are tricks you can do to get more benefit than you lose. The "blood groove" in a sword is good example- it's not so that your sword doesn't get "stuck" because of suction, it's to remove material without reducing strength much. Where exactly you start to lose more than you gain, I'm not sure. It's a tough question because it's so far outside the realm of possibility. A trained combatant could probably adjust their style with such a weapon, favoring certain techniques over others, but I'm not exactly sure how you'd represent that in-game. Maybe a boost to Attack rolls but a penalty to damage?

Regarding sharpness, I'm not sure this is something you really need to worry too much about in-game. Hardness IRL is definitely an issue, but here it's usually a trade-off between the ability to hold an edge and the ability to flex and bend without cracking, and as you go more towards one you get further away from the other. You could read about some of the Japanese techniques that combine steel of different qualities in layers, though I'm not sure how much of that is applicable to other schools of crafting. And also japanese swordmakers didn't spend hours and hours forging swords because they were in possession of some super-secret special knowledge that allowed them to make awesome sword that could cut through a tank, but because (based on what I've read) japanese iron ore was **** and they needed to spend much longer purifying it before they could actually make a sword and not a sword-shaped piece of gravel that would come apart at the first stroke.

Anyway, back to sharpness, there's a lot of bad swordfighting in Hollywood (just like there's a lot of other bad things, too) because they make for better movies, but from what I've read about medieval combat a lot of it involved around techniques to get your opponent off his feet so you could pin him down and use a dagger to stab him through gaps or weakpoints in the armor. It doesn't matter what weapon you're wielding, you're not easily slashing through heavy armor (except maybe with a lightsaber :smalltongue: ). The point is, you don't NEED or even WANT to sharpen a sword to a "razor" edge because that just means it'll chip, crack, or bend basically instantly.

And another thing, shifts in weapons, armor, materials, and tactics often changed in ways that people don't get when looking back at "the past" as one big amalgamated lump. Yes there was a certain amount of fantasy-kitchen-sink going on depending on what you had access to, but people weren't stupid and could see when something wasn't working.
For example, as metallurgy improved and plate armor became more accessible, the added defense meant that you no longer needed a shield. At the same time you need MORE power to hurt enemies in plate-armor, so in combination with that you also got more a shift to heavy twohanded weapons like zweihanders and pollaxes (or at least maces and handaxes) and fewer swords.
Conversely, when the spanish conquistadors arrived in south american they realized that they didn't need the protection that a metal breastplate provided, but it would drown you in your own sweat as you marched through a hot, humid jungle. So (again, going by what I read) most of them swapped to something like a cloth gambeson. That kind of thing- discomfort, isn't well represented in a lot of tabletop games.


Put all this together...and I don't know where you end up. I wouldn't worry to much about "realism". Maybe keep it in mind a little for inspiration, but IMO fun and balance are by FAR more important. Most of your players won't be trained weaponsmiths themselves, afterall.