Board Thread:Questions and Answers/@comment-24951985-20140810105641/@comment-1173941-20140810110135

While I personally don't remember, there was a discussion about this some time ago. It was mentioned that Double Circular was used in the Novel in Kirito's duel against Heathcliff (the first time), but the anime cut it out. The anime has cut out a number of Sword Skills simply to save a few seconds of animation. It's understandable to a degree, seeing as in the Anime, Sword Skills are just a background detail that's not full explained.