Kunai Blade

These are kunai-like blades wielded by Izumo and Kotetsu. They have the general appearance of kunai with similar bases, but the blades instead are curved, elongated and single-edged, giving them similar appearance and function to swords. Each of the blades has a small hole right near its long, bandaged hilt, which at its edge sports a larger versions of the standard ring all kunai have. 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, and one of them was broken during this encounter. During the Fourth Shinobi World War Izumo and Kotetsu again used these blades connected by a chain with a weight in the middle, to attack and sever a revived 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.