User blog comment:Xilinoc/Ch. 598 - The Shooting Star Project (We Only Have To Beat You Mix)/@comment-493809-20140925161411

The problem I see with Letzt Stil being better destruction-wise is that it robs them of their Quincy powers and requires their powers to be re-activated. This could be interpreted as merely burning themselves out, as initially explained, or it could be that it severs the connection to Yhwach. Considering the method by which Uryu regained his powers - being shot in a precise location by a Quincy arrow - it may have been a way of re-establishing the bond.

Also, there are direct parallels between Letzt Stil and Ichigo's final battle with Aizen. The intense power-up, the one-sided fight, the massive attack, and the loss of powers afterwards. Not sure what the implications of that are, but they may be linked.