"ah there's my soul" has the same energy as looking for where your phone is, and turning on the flashlight of the phone in your hand to look for it, and then staring at the phone in your hand until it clicks
Mahoraga: "according to the law, my dear client Sukuna did not actually kill anyone in shibuya, after all the person who committed the crimes had 2 arms, while my client clearly has 4, this makes it obvious that it was someone else in the incident"
You could go with an animal theme for attacks with cursed energy, like claws, fangs, quiles,..., and if there is any curse animal take inspiration from that, having adaptation should let him pick up techniques like that