Blood Blade

You are able to conjure a simple melee weapon in the form of a jagged dagger of solid blood. 

The dagger deals 1d4 necrotic damage. If you drop or throw it, it melts into a pool of blood at the end of the turn. Thereafter, while the spell is still active, you can use a bonus action to reform the blade in your hand. While wielding this weapon, use your spellcasting modifier instead of Strength or Dexterity modifier for your attack and damage rolls.

When cast you may expend one hit die to increase the damage by +1.