User blog comment:Xilinoc/Ch. 639 - BABY,HOLD YOUR HAND 2/@comment-26091912-20150820085132/@comment-5693502-20150821085813

Unlike other characters who just whip out new abilities and techniques from their asses like it's going out of fashion, pretty much all of Mayuri's techniques are fully justified.

For the Letzt Stil/Vollständig thing - at the time, Uryū was a basic Quincy and his Letzt Stil just amplified his basic Quincy powers; he defeated Mayuri with a super-duper-mega-giga Heilig Pfeil. All the Sternritter are Quincies, regardless of their Schrift, (meaning they all have the same ) so you probably can compare both Letzt Stil and Vollständig at the moment since they both pretty much do the same thing i.e. augment a Quincy's power (which obviously also includes their basic abilities).