Her reply almost startles him, which he shouldn't. He should really know her better by now. Rider tenses when she yells at him, but his expression turns stern when she speaks of fear.

He doesn't appreciate the scolding.

"Listen to me now. The path of fear is not the way of the conqueror. Fear has no place in my heart, nor should it be in yours. There is no enemy I cannot conquer, you know this!" It's as much a promise to himself as to her. "Use your command seals if you must. I cannot stop you. But you said it yourself - without honesty, we will not win the Grail. I've always been honest; your utilization of the command seals is not something you're willing to do, is it?"

He knows that much well enough.