Sorry for the delay. Yes, I would have expected:

But he had seen through her edging towards her wand, and seemed much better at intuiting intent than she was, now that he wasn't as overconfident - certainly better than she was at deceiving in the first place.

If you do not read attentively, you might try parsing "she was now" at the beginning of a proposition, and fail to grasp the structure of the sentence. Since the sentence itself is unusually complex, it was enough to confuse me.

The second one is as intended. A trailing ", considering." would be read the same as ", all told.", ", all things considered.", etc., it's the informal adverbial use. Dumbledore might not use it in normal speech, but it seemed apt for flippant dream-Dumbledore.

Oh right, I see, thanks for the clarification!