This is a sword that is used by Aoi Uchiha, it is a sword that has a special function to it. First, it is a weird shaped sword, it has a handle and a blade and is shaped like regular sword, but at the hilt of the sword is a large circle, big enough to fit his head through. He usually keeps this sword in a transformation jutu that makes it look like a regular sword, but when he releases it, it goes to looking like it is suppose to.
When Aoi took it to a blacksmith, the smith told Aoi that the weapon wasn't made from any common material like steel. The smith said it was most likely made centuries ago, using an unknown material, then the smith told him the the power that the sword had it could of possibly been a tool of the Sage of Six Paths, or his decedents.
By funneling his chakra into Sakanade, Aoi can spin it with his finger to cause this state in which it causes any person that looks at it to not know direction through hypnosis. They don't know their left from right, up from down, or front from back. It is one of his tools that he doesn't use unless he has to because of the effect, also it takes a lot of chakra from him. The bad this is that the function of this tool cannot be used again, for a few minute, at most 10. Actually, the sealing tag seals it back into its regular sword form so he can't use it again. It can still be used as a sword, he can use this and Kyoka to make the ultimate pair of dual swords.