A weapon nonmagical metal armors and shields. When you hit a creature with a melee weapon attack, you can choose to corrode either an armor or shield that is being worn or carried by the target. The targeted object takes a cumulative -1 penalty to the AC it offers that last 1 hour. Armor reduced to an AC of 10 or a shield that drops to a +0 bonus this way is destroyed. If the object isn't being worn or carried by a creature there is no effect.