Greater Silver Sword

From Mordenkainen's Tome of Foes, page 89.

Description
''Weapon (greatsword), legendary (requires attunement by a creature that has psionic ability). 6 lbs.''

This magic weapon grants a +3 bonus to attack and damage rolls made with it. While you hold the sword, you have advantage on Intelligence, Wisdom, and Charisma saving throws, you are immune to being charmed, and you have resistance to psychic damage. In addition, if you score a critical hit with it against a creature's astral body, you can cut the silvery cord that tethers the target to its material body, instead of dealing damage.