I think the implication they are trying to give is that he could easily tell everyone before was weaker than him.
Being an Assassin has given him an excellent sense of his enemies strength, and he's completely collected when he already knows he's going to win.
I think what you're seeing is a result of his inner conflict with himself.
We've seen him do what she's described all the time. When facing the Spiders, with Neferpitou, his brother. He simply bolts the instant he thinks he can't win. But he was at least confident that that was the correct course of action.
I think the reaction of this fight is a result of his instincts and training trying to force him to flee, but him forcing himself not to. And it's this that's causing him to look so unsteady. Because he's completely unsure.