The Mimic Sword (5e Equipment)
From D&D Wiki
Weapon (longsword), rare
A sword that is also a mimic. Or, is it the other way around? Anyway, this is basically just a mimic that chooses to let you fight with it.
When you score a critical hit with this magic weapon, the target takes an extra 1d8 acid damage.
Adhesive. When a creature picks the Mimic Sword up who it doesn't like so much, it sticks to that creature's hand, preventing it from using that hand to attack or do anything else. A creature thusly stuck can use its action to make a DC 13 Strength check to detach the sword.