I don't think he's being dramatic at all, he's just treating it seriously. It's a fact that most beginners only think they need to learn how to swing the sword. If the teacher doesn't treat the footwork seriously then the student won't either.
There's a good analogy in video games, everyone knows how important it is to dodge enemy attacks. How much damage you can do doesn't matter if you always die.
Can I just say... She's got it coming for her. She's smart, yes. But naïve and inexperienced. She shouldn't have hid any information from her brother, especially she knows the nature of this mission. Dumb bitch