In honour of Dark Sun being the new setting, I thought I would post the rules I use for non-standard materials being used for weapons and armour. Athas is a world where weapons are made of wood, bone and obsidian more commonly than steel, so this seemed fitting to post.
This is to deal with issues were different material weapons sometimes have confusing rules, ie a flint arrow versus a steel arrow. Sometimes these rules are ignored, and I state openly that rules for different materials should only be used in settings where it matters. If its a medieval Europe game then you don't need to crack out these rules for the one time a warrior picks a bronze dagger from a work bench and throws it. But if its an Ancient Greek setting and there is a mix of bronze, iron and steel it might, and if its a conquistador mesoamerican setting then the comparative power of steel makes it paramount to have these rules.
Materials are all given a few different criteria: Hardness, Sharpness, Weight and Breaking Point.
Hardness is the main factor for different materials. When comparing a piercing or edged weapon versus hard armour (mail or plate for instance) you note the difference in the hardness ratings. For example with steel weapon versus bronze armour its a rating of 1. The effectiveness of the armour is thus worsened by 1 for Damage Reduction for slashing weapons, for piercing weapons the number is different. If it had have been bronze weapons versus steel armour the armour would have its DR Increased by 1.
Sharpness is a number that is used for slashing and piercing weapons versus unarmoured opponents. It is a direct modifier to damage. A wooden sword would have a sharpness of -2, but an obsidian knife would have a sharpness of +1. Steel is used as a baseline (+0)
Weight is used as both a reduction (or increase) in weapon speed (based upon size). For blunt weapons it can also be an increase to damage.
Breaking point is the amount of damage the weapon can give or receive in a single blow (before multipliers) before the weapon risks damage. So a bone spear might shatter easily, a bronze sword occasionally bend and a lead mace may do great damage once, but its mace head will quickly be deformed into uselessness.
These rules both increase flavour in appropriate settings and offer new types of rewards beyond "magic" items. A mithral sword may be mundane, but its stronger material, lighter weight and razor edge make it a great reward on its own.
Welcome to your doom
8 hours ago