Scrodulus said:
I think a lot of people (or just me) misunderstood the "show me your bankai" statement. I think Kensei suspects Hisagi is capable of 'waking up' his Bankai and learning to use it, I don't think he just has one stored up. Nor do I think all the other lieutenants have it either, that would be just... thick.
I believe Shuuhei achieved bankai somewhere during the 17 month timeskip, could have been a motivation to get over Tousen's death. He clearly still hangs on to the lesson "fear the sword" and the bankai of Kazeshini must be something he finds truly horrifying and is too afraid to use it. This is the barrier Kensei will use force to break and beat some sense into Shuuhei. The training is harsh, but that's how the Vizard rule, even they overcame their own fear when dealing with the hollow side.