She'd be shocked to know that he can see she's channeling at all; male channelers from her world can't tell when a woman is channeling, and female channelers can't tell when a man is channeling. Already she's full of questions about how he can form a weapon from water like that, how he's able to channel at all without going mad -- but she pushes them aside, more focused on the inevitable conflict.

"Stand down," Moiraine says, "or you will have to kill me." She means every word; he will have to try to kill her if he wants the fight he's looking for that badly. It isn't so much that she's not willing to start the fight as that she can't -- but she has every intention of finishing what he starts, if he doesn't take her warning for what it is.

Moiraine gestures -- the white light swirls brighter around her -- and Childe's blades simply dissolve. It doesn't even look as if it took her a particular effort. She has no doubt that he can reform them at will, but this is merely to make it clear that she's far from powerless.