Board Thread:General Discussion/@comment-6746577-20131127231527/@comment-13237238-20140101102652

I think the 'fake' zanpakutou Aizen had been using until Kyoka Suigetsu's true abilities were revealed was described as a "Flowing water type" zankpakutou which caused enemies to attack each other, which was stated by the lieutenant of the 4th squad, when her and Unohana first confronted Aizen.

So I'm guessing he had created a fake bankai for this zanpakutou as well