Jellyfish jackets that use photoreceptors to slowly charge a shock weapon. Gangsters walking around with iridescent long coats, casting colors on the walls, indicating a full charge.
Once the trigger is pulled the coat drapes, floppy and dark, until it can recharge.
Which leads to an arms race of developing the look of light-up coats without the weapon, so you look dangerous but the fuzz can’t hang anything on you.
Or faking the light so no one knows you’re out of ammo.