[Calca]

Originally Posted by Knjaz

Easy, even I can come up with a plausible explanation - captains that had their bankais stolen have been developing shikais and other powers that whole time, improving the "energy-efficiency" of their abilities, improving their non-zanpakuto related skills, learning how to fight while not having an access to bankai.

Not sure if that would help Soi Fon's bankai much due to way too different nature of it, but, for example, Hitsugaya's bankai will receive a huge buff with the new "cost-efficient" techniques he developed.

Although, if Soi Fon also learned to better control her reiatsu/increased her reiatsu while mastering shunkou, it will have a direct impact on everything she does. After all, zanpakuto's "power level" is directly tied to the "power level" of it's user.

That's actually not a bad idea and wouldn't criticize Kubo for using that one.