Rapier of the Yellow King

Weapon (rapier), legendary (requires attunement)
  The guard of this slender, sickly, yellow blade houses a snake’s eye that seems to follow its quarry around the room when drawn. You have +2 bonus to attack damage rolls made with this magic weapon. When you hit with it, the target takes an additional 2d6 psychic damage. You gain the following benefits while you hold this rapier:
  • You can understand and speak deep speech.
  • You can cast dominate person (save DC 17). Once
  you have done so, you can’t use it this way again until the following dawn.
  Shackles of Pain. As a bonus action, you can choose one creature you can see within 60 feet. That creature must succeed on a DC 17 Charisma saving throw or become cursed and bound to you for the next minute. Whenever you take damage from any source, the other creature takes half as much damage of the same type so long as it is on the same plane of existence as you. This effect can be removed by any spell or effect that removes hexes or curses. Once you use this property, you can’t do so again until the following dawn.