Could someone explain the joke for someone that hasn't read all of the novel material?
Dunkelfelger is a duchy famous for being obsessed with Ditter (basically knights fighting each other in some way, whether it's comparing speed of killing summoned monster, 'capture the treasure', etc)
The stereotype (which frankly isn't far from truth) is Dunkel men are all unga bunga musclebrains where anything ditter will send them into frenzies while the women are all master schemers.
The joke here is that despite Hannelore being such fluffy bunny in personality unlike other Dunkel folks, deep down she's very much one of them to the marrow of her bone.