Stone weapons would be exempt, but wooden and bone weapons should require the periodic application of oil, rubbed in. Otherwise in the dry Zalanthanian climate, they'd get brittle and start cracking, chipping and breaking!
Does that really need to be coded?
Well... I wouldn't mind having to maintain weapons and armor after using them. Maybe not -every- time, but they should degrade... Armor seems to take a fairly absurd amount of abuse as it is... And weapons seem to either break the first time they're used or never.