Wraithblade

You create a spectral blade in your hand that passes through armor without resistance. This magic sword lasts until the spell ends. It counts as a simple melee weapon with which you are proficient. it deal 4d8 necrotic damage on ahit and has the finesse and light properties. In additon, it treats all targets as unarmered (An unarmered creature's AC is usually 10 plus its Dexterity modifier). It treats creatures with Natural Armor, Unarmored Defense, or similar traits normally.

If you drop the weapon or throw it, it dissipates at the end of your turn. Thereafter, while the spell persists, you can use a bonus action to cause the sword to reapear in your hand.