Dark Sun: The Price of Freedom
House Rules: Weapon and Armor Breakage
If a player rolls a natural 1, they may choose to break their weapon in exchange for rerolling the attack. If the player decides to do this, the weapon breaks regardless of the second roll.
If a player rolls a natural 20, they may choose to break their weapon in exchange for dealing an extra 1 [W]damage in addition to the crit damage and other damages added by a crit.
If NPC’s roll a natural 20 against a player, their AC bonus from that armor is reduced by 1. This effect is cumulative. This penalty cannot be greater than the AC bonus the armor provides. To determine the cost of repairing this armor, figure out what percentage of the armor’s total bonus has been reduced (a -1 AC on leather would mean 50%), and multiply that by half of an unbroken armor’s cost. That cost will be detracted from group gold rather than character gold.