Crimson Carver

You make a small incision on your hand, and from the incision a blade forms in your hand. This magic sword lasts until the spell ends. It counts as a simple weapon with which you are proficient. It deals 4d4 necrotic damage on a hit. On your turn, you can sacrifice one damage die in order to heal 1d4 hit points. If the weapon has 1 damage die left and you use choose to heal 1d4 hit points, the weapon goes back into the incision you made on your hand and the incision is healed.

At Higher Levels. When you cast this spell using a 4th level spell slot, the damage and healing dice increase to d6's. When you cast it using a 6th level spell slot, the damage and healing dice increase to d8's. When you cast it using a 8th level spell slot, the damage and healing dice increase to d10's.