Responses
I agree with everything you said! Uri is asked to be a Duke but she hides everything from him making him as you rightfully called "a crippled puppet." More than caring for him, she is only gratifying her wishes while making it look like she is the one sacrificing. A sacrifice so useless that it is benefitting no one.
Fr. Almost nothing beneficial comes out of her "sacrifice". She's just forcing her brother to do something he doesn't want to do.
I don't like Lamia... She has too much bravado.
She claims to become a knight and avenge Uri, while a abandoning her role as future duchess for some unjustified justice which she could gain through obtaining the title of duchess.
She says Uri will be the future Duke but neglects him, hides things from him and he is eventually a crippled puppet for his sisters self-gratification.
Aquila is also in the wrong for provoking her instead of going for things the right way... But I also get that having seen the love of his life die continuously could have messed him uo