Swarm Knuckles

As an action, you can summon your swarm to your hands, creating a living brass knuckles. When you make an unarmed attack or an attack with other forms of brass knuckles, add 1d4 piercing damage to the attack. The effect lasts for the duration, until you dismiss it as an action, or until you take damage. The swarm is dispersed if Gathered Swarm is used. 

Upon a successful attack you can use your bonus action to send the swarm from your hands onto the target, dealing 1d6 piercing damage and giving the creature disadvantage on savings throws until your next turn. This ends the spell.