I was literally about the to comment something about that saintess. Why the heck was she let free of nothing when she tried to harm an imperial Duke?? Like whyyyyy is it bc they did not know she was the one who tried to poison him?
to my understanding, the duke was a nuisance to royalty bc he was too powerful. his fiance suddenly became the saintess while conveniently having an odd relationship with the prince, whom she conspired with to kill the duke, both breaking her engagement (to marry the prince probably) and taking one of the prince's problem away. I may be wrong but thats what I think it was about, too lazy to reread though.
Yes she wasn't punished because it was the royal family who plotted to have the saintess murder the grand Duke and then marry the prince, pinning the blame on someone else. She hated Ferzei because he was indifferent to her. She suffered an unrequited love which is why she decided to get with the prince who considered Ferzei to be a threat. Ciel described Ferzei as a "subvillain" in the first chapter but didn't really describe it much since she went off on a tangent about how good the pay is and how the workers are treated well. I thought it was strange in the beginning too that the saintess was someone who schemes but I suppose that's just because of the perspective of the original novel...
We didn't know much about Ferzei ex fiancee. She's a saintess but isn't she the one who planned to kill him. The only thing we knew is their engagement got broken off. She tried to harm a duke and prince's cousin. But the story never explained if she was punished or anything. Maybe she's a possible villainess? Correct me if I'm wrong or if I missed some information