Got late so there is little for me to put to discution (still recovering from a minor car crash I have yesterday...)
Any way, the chapter brought me light about that Detergent
Aside from the Zaraki vs Unohana battle, Kubo finally explained in the manga how zapakuto come into existence and how they get their unique characteristics. Altbeit it makes Ichigo having a sword from the beginning a bit weird. As if Ichigo's soul had been given a (perhaps Asauchi) zanpakuto before his birth.
The explanation about Asauchi makes sense when you think on why Ichigo was never able to seal Zangetsu.
Zangetsu has never being an Asauchi before. When Ichigo draw Zangetsu from his soul he didn't do it through an Asauchi so Zan was manifested directly in to it's released form.
It seems like the zanpakuto can be released to shikai once they're already been sufficiently "imprinted" with the wilder's soul, once they become an extension of the shinigami.
Because never was given an Asauchi to Ichigo when his power manifested it was directly to a release form...
Kenpachis dialog was to deep... much intense panels. Great job sensei... waiting for more on these two