Moonsteel Rapier

The blade of this magic weapon seems to shine from within with a pale, white light. The weapon deals an extra 1d6 radiant damage to any creature it hits. If the creature is a shapechanger or any other creature not in its true form, it becomes frightened until the start of your next turn. At the start of its turn, a creature frightened in this way must succeed on a DC 13 Charisma saving throw or immediately return to its true form. For the purpose of this weapon, “shapechanger” refers to any creature with the Shapechanger trait.