Cause Decay

Your touch causes nonmagical objects to degrade, as if suffering years worth of decay. This is enough to outright destroy tiny or small objects or cause 2d10 points of damage to medium or larger ones. Weapons that you touch will take a 1d4 penalty to attack and damage, while armor will take this penalty to AC. If the attack penalty reaches -5 or if the AC bonus is reduced to 10, the object is destroyed. 

You can target worn or held objects, but you must make a melee spell attack against the holder/wearer in order to do so.