User blog comment:Xilinoc/Ch 649 - The Theatre Suicide SCENE 3/@comment-4221851-20151107002522

After reflecting and going through the Starrk vs Kyouraku fight, I remembered when Starrk pointed out Kyouraku's different hand speeds. Now, though this may be anime-only, Kyouraku says he uses the wakizashi to wear down his opponent before surprising them with the final blow of the tachi.

Considering the Zanpkutou Rebellion Arc's depiction of a manifested Katen Kyoukotsu became canon, it may be a bit of a small leap to state that Shunsui's initial Bankai was all meant to be sudden, grand, one hit kills with a mirror-wound effect for Shunsui and his opponent. Think of it similar to the final act before suicide: that single moment of shock from the intended action before the end. This would make Shunsui's sword style in the anime canon and give potential hints to Kyoukotsu's Bankai Power, being something swift, hard and capable of leaving his foes at his deadly gaming mercy.

Of course, this makes the assumptions that A) Kyoukotsu is truly Nanao's Zanpakutou, B) Kubo makes Kyouraku's anime-only explanation of his sword style canon and C) Katen and Kyoukotsu have independent Bankai and/or Shikai techniques. Pending further info we'll find out I suppose but I had to put this out as an idea.