Kaiser Blade

The Kaiser blade is a powerful sword created by Kisekiteki Hyuga, shortly before the founding of Konohagakure. According to Kisekiteki, he only ever made two, and gave one to Madara Uchiha; however, Madara's was supposedly destroyed during his fight with Hashirama Senju, leaving Kisekiteki's as the only one left. Kisekiteki voiced his disinterest in creating another one, due to how much power they hold, and his fear that it would one day fall into the wrong hands, like it did with Madara's.