Another take on weapon and armor degradation

I won't go too far in saying that dungeon crawling in D&D is basically as much a game of exploration and interaction as it is a game of resource management. Indeed, the more time passes in a dungeon, the more turns are accumulated, and the more torches burn, fatigue lurks, spells are exhausted, and the pressure of wandering monsters is strong.

Weapons and armor are not part of this resource management, so here are two simple rules that allow weapons and armor to get damaged with time. 

Damaging armors

Each time an attacker roll a natural 20 against a player character, the PC's armor lose 1 point of AC until repaired by a competent craftsman.

Damaging weapons

Each time an attacker roll a natural 1 when attacking, his weapon suffers some damage and is down to the previous dice type. A d8 sword become a d6 sword; a d6 mace become a d4 mace, and a d4 dagger is broken. A competent craftsman can repair the weapon for 20% of his base price by dice type lost.

And if it's a magic item?

Maybe the magic items cannot be broken that way? GM choice! If they can, roll a d6. If the result is less or equal than the magic bonus of the item, there is no loss. If it's superior, the item is damaged.