Heiki's Weapon

weapon name: Karasuhebi (Black Snake)
description: Karasuhebi is a black wool scarf that ate the Gen Gen no Mi. The scarf, wrapped around its owner's neck, attacks using the sting at one end and grabs or blocks using the end that looks like a hand. Like Spandam's Funkfreed, it can communicate with others and "have a personality" using the face made by its own illusion technique.
weapon special abilities: After hitting the enemy three times with the sting or licking the enemy once with the tongue, Gen Gen no Mi is in affect.
personality: Karasuhebi does not show himself to anybody except to people that his owner trusts or allows to see. He is an arrogant braggard and likes to pick fights with others around him. Because of the contrast in personality between him and his owner Heiki, they get into arguments often, but in battle, they are undefeatable when it comes to teamwork. He tends to be a bit of a pervert.

Its illusionary, right? How does it autonomously attack?

What do you mean? The two weapons (a sword and a gun i think) that had "eaten" a devils fruit in the manga were able to move on their own like pets except they need commands... I guess, so the scarf would move like that as well.