Psiblade

At-will, swift, concentration; you manifest a psychic blade made of pure mental energy. The blade is a magical weapon that you can use to attack enemies. When you hit an enemy with the psiblade, the enemy takes medium psychic damage, as well as disadvantage to the next Int, Wis, or Cha roll (your choice) that the target takes within 3 rounds.

On a critical hit (or sneak attack), you inflict a greater effect: either Feebleminded, Meek, or Addled (your choice) to the target for 1 round per Rogue rank.