User blog comment:Xilinoc/Ch. 595 - Rubb-Dolls 2/@comment-24031741-20140905175001/@comment-5398287-20140906152229

Apparently, it now produces enough blade petals that As mistook it for Senbonzakura Kageyoshi, which would explain the increase in power. I'd imagine Byakuya achieved this by making the petals even thinner, therefore allowing him to make more from his single sword.