Dark cloaked lightless slash

The once you activate this spell  the weapon that you your holding becomes pitch black with dark as you strike. once you strike as long as the blade does not hit anything a shape of the blades curve travels out in the direction that you swung on hit the dark curve will do 1d12 slashing damage The attack deals an extra 2d6 necrotic damage to the target, which becomes visible if it is invisible, and the target sheds dim light in a 5-foot radius and can’t become invisible until the spell ends. 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the extra damage increases by 1d6 for each slot level above 2nd.