Armed Saber

Armed Saber (装甲声刃（アームドセイバー）): The Armed Saber is a device created by Kogure Konosuke that can greatly increase the power of an Oni. By pressing the button on the bottom of the saber, Hibiki is engulfed with a fiery aura. Disk Animals swarm to him changing into his armor as he transforms into Armed Hibiki. It is known as a "forbidden device" due to the fact that it can cause an Oni to lose their transformation power if used by someone who is not strong enough yet. This happens to four Oni in the series, Shōki, Danki, Todoroki and Hibiki but they are all able to regain their power through intense training at the hands of Kogure.