Kunai Blade

These are twin kunai-like blades wielded by Izumo and Kotetsu. They have the general appearance of kunai with similar bases but the blades instead are curved and elongated, giving them similar appearance and function to swords. They are usually carried by Kotetsu, bandaged and strapped to his back.

They were first seen when a team from the Nijū Shōtai led by Asuma encountered Hidan from the Akatsuki. Kotetsu and Izumo used the blades to attack Hidan one of the blades were broken during this encounter. During the Fourth Shinobi World War Izumo and Kotetsu again used these blades which were connected by a chain with a weight in the middle, to attack and sever Kakuzu's hands.

Trivia

 * Though signature weapons of Izumo and Kotetsu, these blades aren't unique to the two, as it is a generic tool that is also used by others.