Nemesteel Weapon

Weapon (any melee weapon made of metal), legendary (requires attunement)

These weapons are made of an iridescent grey metal from beyond the stars.

While you are attuned to the weapon you (and only you) can lift it. In the hands of all other creatures, the weapon’s mass is considered infinite, though it still retains its ordinary mass when falling or being transported. When you deal bludgeoning, piercing, or slashing damage with the weapon, you deal additional thunder damage equal to the damage dealt. Additionally, targets reduced to 0 hit points by this weapon detonate in a harmless (but cacophonous) explosion.