well, it just happened right before she acted least stupid ever.
it was even a decent battle, even if she never had that much control over Aria...

so, basically, Siegfried sets the girls out on the journey, planning that they'll steal Aria (one way or another), and then they'll give the weapons to his blond 2nd in command (who I can't tell if is a man or a woman), and after that.. well, screw them, they've filled their purpose.

Other than having Boobily powering up, I don't see much point to this arc, we didn't even learn something about the empire.

two last things... Boonbily wears her breastplate for dinner? really?
and why can Aria create shockwaves underground, it's so unfair that no other sword can do all that.