@Tatsuya-Kai If there's one promise in the world you can break any day, it's one that was blackmailed out of you or otherwise gained by using foul play. But again, I can't really hold it against Estrella due to her circumstances.
Whatever happened to the knight who already fought once against the demon possessed dude? He, like, never reported it to anyone, despite surviving. It's like during WW2 a British soldier in some British village near an airforce base comes upon some suspicious dude with an exceedingly German accent, has a fist fight with the dude, but then both leave. The British soldier never reports it to his superiors or gathers more troops to look for the man again, because... Because the plot of this story.