The group I DM for my hombrew game love to loot anything and everything that isn't nailed down. However, this makes it hard to give bosses cool/powerful weapons without them taking it and breaking the game. I've tried counteracting this by having them fight mostly magic users and monsters that use claws or fangs. It feels cheap though to just tell them "you can't have this because reasons" or having the weapon miraculously break after the fight. Any ideas on how to avoid this problem?