Vampiric Blade

You create a black shadowy blade that appears as either a dagger, short sword, or long sword of your choosing and when the sword comes in contact with an enemy it deals 2d6 Necrotic damage. You can store the blade within your shadow to call upon it again as a bonus action but when you do you take 1d4 necrotic damage the amount of neurotic damage you take is increase by 1d4 for every level higher spell slot used to cast it. (calling upon this spell in this way does not take up a spell slot) When you cast this spell using a higher level spell slot than it you add 1d6 necrotic damage for every level higher.