The sword would be no good if Itachi had him in his gaze.....and if he closed his eyes then he would have trouble striking Itachi's chakra
The sword would be the least of Itachi's worries.* Kisame has created multiple sharks before in his shark jutsu that seem to act on their own.* Itachi's in the clear if he uses the sharingan. But what i'm saying is*the tsukoyomi is a genjutsu technique enabled by the mangekyo sharingan.* Even though it's using the sharingan, genjutsu is a focused technique.* Leaving openings from behind.* Even with the sharingan, Itachi would have to switch between both. I doubt that technique would be used.