Strike an enemy, adding your proficiency bonus to the damage. Moreover, if the attack hits, it deals an additional 1d6Psychic damage. This attack doesn't break concealment.
Note that "not breaking concealment" means that while solo and Hiding, you can attack the target without entering combat. This lets you get two attacks off before they're even aware of your presence, which is excellent for assassinating isolated NPCs.
Sword of Clutching Umbra, and 
Justiciar's Scimitar.
Psychic damage. This attack doesn't break concealment.
Action
1d6 (1~6) 
Attack roll
Range: Normal weapon range
Recharge: Short rest
