Board Thread:Theories and Speculation/@comment-25645405-20150719020101/@comment-27074627-20151017141144

Stop screwing nonsence. Firstly, Sasuke really has never synced his eyes with anything. Seconly, it was never said Sasuke awakened Amaterasu in the left eye thanks to Itachi's sealing. But the description of Transcription Seal: Amaterasu implies this jutsu is actually one-off jutsu, which can't work permanently. It's supported by Sasuke's left eye taking design of Itachi's MS during the technique's activation (and Sasuke uses Ama consciously only with his own MS). So we should assume Sasuke awakened his own Amaterasu in his own MS all by himself, and Itachi has nothing to do with it. And there's absolutely no proof of Itachi having the ability to give any of his techniques to a person for permanent and conscious use, although it's also true that Sasuke would become too op with Totsuka Blade/Yata Mirror.

By the way, it was already said these weapons are tools (albeit ethereal) and not some kind of jutsus. Black Zetsu confirmed this too, when he said Oro was seeking Sword of Totsuka as one of the forms of Kusanagi Sword, which is a tool without a doubt. Also if it was a jutsu, he would be searching for the way to learn it, but not for the way to acquire it. Any other speculations are just fanon thoughts.