The more images of Niele’s outfit I manage to find and the more I have her “reasons” for it explained, the less sense she makes.
As nibelung informed us, she’s not even choosing to dress like that, her magic staff MAKES her clothes transform into… whatever that’s supposed to be.
She even gets berated for being coerced into wearing only belts. The speech bubble in the fourth image translates to “Don’t you have any shame?”.
Because that’s so totally is a fool-proof excuse for having a character run around virtually naked: “
A wizard magical artifact did it!”