For my home brew campaign, the different tech levels of various civilizations has an impact on the materials used for weapons and armour. I've been looking at rules for this, and had hoped for input in the new DMG, but it is only for futuristic weapons. I was also hoping for a 'quality system'. But they might be saving both elements for a supplement 
Therefore I was hoping for you input specifically on how to make bronze/copper and bone/stone weapons work, without over complicating combat. I for example don't want them to deal less damage, as that would skew the challenge rating. Having different effects in the different combinations I would also like to avoid. But still the difference has to be meaningful.
The campaign takes place in the 'New World' with characters being a bit like Colombus or Cortez arriving in a new continent far from home and normal logistical support, but with more ancient ruins than what was found in North America. Therefore the elements of having the right gear/weapons/armour becomes relevant.
(Treasure and trade is another issue, but that is for another post).´
Weapon quality and material
As not all cultures have the same level of technology within manufacturing of arms and armour, different enemies will have different weapons and armours made from various materials with various properties, strengths and weaknesses. As to not skew the combat rules overly, most of the materials have their most significant impact on weight, price and production time, which can be important far from civilization.
Damaging and breaking weapons and armour
Whenever a combatant rolls a natural 1 in combat with a weapon, not made from steel, he has to roll a DC 10 DEX check to avoid the weapon breaking. If he succeeds the weapon still needs servicing for at least a short rest for it to be functional again in combat.
Whenever a combatant is hit with a natural 20, his non-steel armour gets damaged and he loses 1 point of AC, until he spends a short rest mending the damage.
Steel
Steel can in the old world (almost) only be crafted by dwarves, who knows its secrets and can create the temperatures necessary. Their arms and armours are highly prized, also among its enemies, and can easily fetch twice or thrice the price of regular iron forged weapons.
Steel weapons don’t need to roll for damage or breakage, unless fighting against a foe with magical weapons or armour.
Medium and heavy steel armour weighs 10% less than iron armour, as it needs less material for the same level of protection.
Iron
Iron weapons are the default weapons in the Player’s Handbook. They comply with the breaking and damaging rules above.
Full plates cannot be made from iron.
Copper & Bronze
?
Stone & bone
?
As a player, having my character's weapon break really sucks! It is one of those things where the lack of fun is way out of proportion from what you might think. Please ask your players about this before you use such rules.
Weapon breakage used to be a part of dark sun's rules and it made sense there as characters normally started with access to that level of weapon. I can't see it causing too many problems, and it will push the players to gain steel weapons ASAP.