This summons an energy dagger that moves depending on the user's hand movements and thoughts.

You summon a magical dagger, hovering above your shoulder. 

As a bonus action, you force a creature within range that you can see to make a dexterity saving throw as the glowing blue dagger flies towards them. The creature takes 5d8 force damage on a failed save, or half as much on a successful one. This dagger lasts 1 hour, and can be dispelled without using an action.