Blade of Lucifer

You conjure a blade of unholy light. The light is red and violet and the blade is about the size of a longsword. As an action on each of your turn, including this one, you can use this blade to make melee spell attack against a creature within reach. On a hit, a target takes 8d8 radiant damage and must succeed on a constitution saving throw or be blinded until the end of it’s next turn.