I think this would be a good way to bring Humaktis back to earth (slight pun intended).
The first time they Trance against a non-chaotic enemy, and a yield is called, they have to firstly roll Listen checks (modified down for a - in battle, b - in Trance), then Opposed Passions (again modified, because the Hate Lunars is,already in battle,, and has possibly wounded/killed someone). Also, Humakt is *the* death bringer, not the mercy-giver. (Obviously, roll against Honour).
The upshot is - if Humakti go on Tranced killing sprees, then the long term consequences can be terrible. "There was a terrible misunderstanding, and YOU killed the emissary and all their guards while in Trance, *after* they yielded".
Exile? Execution? Reprisals? Give up all your gear as weregild? Dishonor to the clan/tribe/family (which may be irrelevant, depending on how much you play the separation aspect).
Other than the seriously increased chance of dying early, there's a really good reason not many join Humakt, or for their lack of popularity in civilised society.