A semblance is the very manifestation of a persons soul, and as cool as that would be, I just can't see it, because that doesn't fit Jaune at all.
Fit or not, I think the fact that he hasn't found it by now is because he's looking in the wrong place.
I think it might be more along the lines of... he doesn't quite know who he is yet, not completely. We've barely scratched the surface of the puzzle that is Jaune, and I have the feeling that the only person who's going to be able to drag the true Jaune out is Ruby. (Or one of Salem's generals, cause that seems suitably epic)
Pretty sure Dragonbait was making a joke. What's odd though is that one of the episodes is called Jaunedice!!
I think Jaune's semblance is either damage reflection or temporary invulnerability. Shown at 0:55 - Possibly his semblance
Damage reflection seems like the most likely. Either that or his skin momentarily turns to something hard like diamond.
I don't think that's his semblance. Pyra mention he has a lot of aura the first time she triggered it. I think most of the time he's only using a portion of his aura at any time. When Cardin struck him that was a simple aura block, but possibly with more aura than he ever consciously uses.
I swear, this whole genderswapping thing just keeps following me around. Tonight, my D&D character got turned into a girl!! XD
You know, if I was turned into a girl, I don't think I'd be mad about it. It seems like it would be a rather novel experience all things considered, sounds fun.