User blog comment:Xilinoc/Ch. 616 - Mimihagi-sama/@comment-24031741-20150219195423/@comment-26091912-20150220074654

@VinnyLam

Aizen may possess his original spirit power, but he no longer has Kyoka Suigetsu; it disappeared along with his Hogyoku power. Aizen himself even said all the power he acquired was disappearing, after Urahara's seal took effect. So, he obviously didn't fuse with his Zanpakuto. In all honesty, he doesn't even need one.

Look how easily he disposed of Komamura with Kido: