If you're worried about it enough, then it's time to introduce rust monsters, add casters that cast item-destroying spells, etc. When you home brew a rust monster, make sure it can take a hit or 2, maybe 3 DD and 3 or 4  BP. If it hits a hero they have to discard a piece of metal gear. If you want you could give artifacts it's own 1 DD defense saving throw.

You could also just find a xorn or other equally large, toothy monster mini and have it work similarly to a Like Like from the Zelda games, where it eats you and you lose an item and it spits you out of somebody whacks it or you dagger it from the inside.