Board Thread:Theories and Speculation/@comment-27924662-20160409212201/@comment-9782468-20160409225947

And Totsuka requires a swing.

Amaterasu is more unavoidable because it's much harder to see coming. In fact, you can't see it coming unless you have some sort of Sage Mode or Lightning enhanced reflexes.

The Totsuka Blade is swung, so you can see it in its arc and avoid it that way.