Board Thread:Questions and Answers/@comment-118.211.8.204-20150302141811/@comment-4270236-20150319154345

There's also the point that Kirito believes that Yuuki is strong compared to him, since he did say that if she was in SAO, she wpuldve been the one to achieve Dual Blades rather than him. Buuuut, there's no proof to back that up.