The horse gave no response, which was as much of a response as anything, from a horse: she was accepting what he'd said, and continuing to do what he wanted, and made him look good instead, as Sif obviously looked please.
"Nice, nice, that's much better!" She was forgetting she wasn't supposed to be training him, evidently. "Want to take it to a canter? Your two-point's set for it and she's very even-paced. Don't feel pressured, though, if you're not ready."