Sonic Fist

The sonic fist appears to be a sculpture of an iron hand with crystal-studded knuckles curled into a fist. However, when a creature handles the disembodied hand, it flexes its fingers before once again bringing them into the fist. When attached, the hand begins a low chant in combat. This seems to be a sort of hymn in a strange language which grows louder and louder as the fight progresses. You must remove one of your hands and replace it with the sonic fist. This can be done during a short or long rest. Once attached, the fist is a light, finesse melee weapon in which you are proficient. It deals 1d8 bludgeoning damage and 1d6 thunder damage. You gain a +2 bonus to attack and damage rolls with the sonic fist.
With the sonic fist attached you can use your action to create a 30-foot cone of sound. All creatures in the cone must make a Constitution saving throw (DC 8 + your Constitution modifier + your proficiency bonus). Creatures who fail the save take 6d8 thunder damage and are deafened for one minute. Creatures who succeed take only half damage and are not deafened. You cannot use this ability again until you have completed a long rest.