The behavior of Edwin is shockingly stupid. It is hard to believe that he is the son of the king and queen. His parents showed a lot of savvy in the way they publicly challenged Yumiella with their knight captain and had the court mage talk about dark magic in order to dispel suspicions in front of the rest of the nobility.
I loved the field exercises this episode. From Yumiella losing rock, paper, scissors against her own dark bind to offering potion only to then decide it was a waste and traumatize people with her dark magic healing anyway. Finally, I love the twisted logic she used to convince people to allow her to blow the flute again. It was either that or she injures each of them (she is pretty sure she can do it without killing them after all).