Board Thread:Episode Discussions/@comment-1181222-20170823100207/@comment-5085906-20170826160952

Berserkchart486 wrote: But the sword isn't the Kusanagi. It's some random blade at the moment. Remember, he lost his Kusanagi fighting Kaguya. Zai no Sho says and I quote: "He [Sasuke] wears a vest under his cloak. He also carries the sword of Kusanagi in his back. Furthermore, his left arm appears to be still missing."

It could very well be a databook error. But it is causing a lot of confusion. I am not sure if I should provide a link, but you can just Google Zai no Sho translation and you'll see for yourself.