Well, he is technically the khagan, winner of the Nadaam. While such things mean little and less to her own people, she would know enough to know the horns are not likely to be the reason for his fascination, Ishgardian or no.

"How?" it's not an unkind question in the slightest, still said with that tone of a kind of wonder, "I... was given to understand such while such jobstones were not lost so much as scattered, ones with the power to teach such a discipline were... rare."

Singular, actually, but if she doesn't actively know about Sidurgu, he won't be the one to betray that confidence. He wouldn't put it past the bastard to have taught someone else and just never said a word to him about it.

And if she learned our way?

He doesn't have an answer for that, not even in his own head.