@Zblurth Yeah, I was wondering that too. Why did he bother negotiating with her release as a good of theirs, rather than a service of his? They want it gone, and it clearly affects their surroundings poorly, so they should be quite willing to let her go with him (if he guarantees she wont return)
and pay him in return.
And then he wants to endanger her life by suddenly changing his mind and making it a duel instead of releasing her in return for starting at equal standing? I suppose the duel is to make them lose (as otherwise she is dead) and start as a weak party who lost to a child. But it still is endangering her for no reason, going back on his deal (granted, it was never accepted, so he wasn't bound by it either), and unlikely to be accepted anyway as if this was enough reason to incite action then she would have been killed off since long ago already (the curse is an intangible fear that makes them avoid it unless ready to actually sacrifice someone for it).