It looks like the Sternritter aren’t the only ones confused by Yhwach’s sudden announcement. Ishida also questions why he would be named as the successor to the throne, but Yhwach’s quickly makes it clear that Ishida has hidden strength that far surpasses even his own. In addition, it was no accident that Ishida is a mixed-blood quincy: he was actually the sole survivor of the “selection”, the purge a decade ago that killed all the mixed quincies, including his mother. For whatever reason, this difference was enough to draw his attention and convince him of Ishida’s latent potential. It looks like it’s finally his time to shine. Of course, Yhwach’s cares little of the internal dissent that his announcement as stirred up, and as Haschwalth deduced, he was actually being intentionally vague and using the distrust to ensure Ishida’s loyalty. He cares little for his subordinates, and this attitude seems to have trickled down to some of the Sternritter, such as with Bambietta, who vents her frustration at the situation by cutting a subordinate in half after luring him with promises of sexy times. Given that it’s not the first time she’s done something like that, these guys don’t seem too bright.
On a side note, I found it amusing how most of the female Sternritter have upgraded versions of the Vandenreich uniform (very form-fitting trench coat, short skirts, tights, etc.). Sadly, I really don’t think a lot of them will amount to much more than eye candy and cannon fodder, with a few exceptions. This is only reinforced by the progressively more ridiculous names and liberal use of alliteration in many of the quincies (Candice Catnipp? Mask De Masculine? NaNaNa Najahkoop??). However, I do find it impressive that Kubo can come up with so many character designs even after ten years. Just the 26 members of the Sternritter, not including Yhwach, makes for a huge cast of villains, though the large majority of them will probably not be too significant, as was the case with the Arrancar.