Right, exactly. I can't say that's for sure that's what happening, but... given that what I felt was definitely bloodbending, that must be what he was doing.

...And I can definitely imagine why he would elude discovery as a waterbender, too. Given that bloodbending's illegal in places that have, well, laws, I'm effectively the one person who would recognize the sensation. I imagine he's been using it very subtly to spin fights in his favor.