Thread:B214/@comment-203.87.147.234-20170224021028/@comment-30924344-20170224023352

AxA would refers to Issei's first power which is the Boosted Gear before Balance Breaker was achieved and also ExE seems to be a future powerup [probably his great red one] as well.

Azazel did state Issei's powerups go like this: AxA [which i believe stands for Something x Awakening], BxB which stands for Balance Breaker, CxC which stands for Cardinal Crimson, DxD which stands for Diabolos Dragon and ExE [which I believe stands for Something x Emperor].