Ugh, it was really badly written, especially the sudden change of the character. But more so I really cannot understand Nanao's behaviour and emotions. Is she depressed that she lost her friends and she survived, that she didn't kill the enemy general or that she frenzied during the battle? It is really not explained that well.
She doesn't really behave like it was about her friends, she couldn't honestly expected to kill the general so why exactly is she is on such bad state? So the only reason is that she was rescued in a petty way? So why not refuse the magician and stay there protecting her honour?