So I've read the novels as far as they're translated and this manga, but I'm having difficulty understanding the coup. From what I gather Lux wanted to change the empire, so he and that "older brother" planned the coup, but it seems Lux wanted to do it without killing anyone, while somehow the "brother" made it so all the 1200 drag knights would be dead. Not really clear about that, but what I'm more interested in is how was Lux imagining a coup, changing the thinking of the empire without killing anyone. I know there exists bloodless coups, but I don't think that's possible with this empire.
Or, I just got it all wrong, and that's why I don't understand, so correct me then.