Board Thread:Questions and Answers/@comment-24826159-20160125220341/@comment-27565137-20160130022134

Alaba wrote: in chapter 528, isshin told ichigo that repairing his bankai wouldnt be possible as he did not know anything about his true self, why would this matter?

Because an Asauchi just like Old Man Quincy explained to Ichigo during his training to reach bankai. When he materialized all those swords, Old Man said "These are all pieces of your soul, each represents an aspect of yourself, and only the aspect of you that's made purely to fight can defeat me."

In a way when Ichigo fought the Asauchi's and lost was because he didn't know himself. There were still a lot of doubts clouding his mind, even if he didn't think about the questions and answers.

That's why he needed to know himself. Because only knowing himself could he let go of all doubts and find his center, his fighting spirit, where a shinigamis true power lies.

That's also why when Ichigo went to round two, we see all the Asauchi's kneeling before Ichigo. Because they recognized what was really in his heart.

Has the name itself hints Asauchi means "hollow or shallow blade" meaning they need to be filled with the fighting spirit of the person. If the person heart is filled with doubts and Ichigo was filled with doubts, even more so after Yhwach words, he wasn't able to really focus the first time around.