Metal is scarce in Athas. Metal weapons and armor cost five times as much, while non-metal weapons and armor can bend or break in use.
Weapons
When you critical fail with a weapon attack, you can choose to reroll the attack. If you do and your weapon is nonmetal, it breaks. If your weapon is metal, it breaks if you fail the reroll.
A broken weapon can be repaired by a successful Repair roll and one hour of time.
Hardore Version: You must take the reroll
Armor
Non-metal armor is cheaper than metal armor, but risks long-term damage. In game terms, any single blow which inflicts 2 or more wounds to the wearer in a single hit has damaged the armor, reducing its effectiveness by 1 point. If the armor reaches +0 Armor, it has been so badly damaged it is useless until repaired.
Damaged armor can be repaired by a successful Repair roll and one hour of time.