Unquiet Dagger

Weapon (dagger), very rare (requires attunement by a spellcaster of evil alignment)

Forged by creatures with firsthand knowledge of what lies between the stars, this dark gray blade sometimes appears to twitch or ripple like water when not directly observed. You gain a +1 bonus to attack and damage rolls with this magic weapon. In addition, when you hit with an attack using this dagger, the target takes an extra 2d6 psychic damage.

You can use an action to cause the blade to ripple for 1 minute. While the blade is rippling, each creature that takes psychic damage from the dagger must succeed on a DC 15 Charisma saving throw or become frightened of you for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. The dagger can’t be used this way again until the next dawn.