The blade is incredibly delicate and fine, and is always cold to the touch.

You have a +1 bonus to attack and damage rolls made with this magic weapon.

On a critical hit the target takes an additional 2d6 necrotic damage and you heal an equivalent amount.  The target is prevented from regaining hit points until your next turn.

You can use your bonus action to return the dagger to your hand, so long as it is on the same plane as you and is not contained in anti-magic field.  

Proficiency with a dagger allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, Damage, Combat, Finesse, Light, Thrown