I generally hate to speculate on these things, but having said that, heres my tuppenceworth.
If its true that the 737 was climbing throught the embraer flight path with a significant pitch attitude, and the emb was straight and level, then a scenario which fits its that the emb winglet clipped the horizontal stabaliser of the 737, not the wing. Neither would have seen each other, apart from the emb would have seen the 737 flash over his head for a few milliseconds. The winglet could concievably remove the entire stabalizer, but even if not at that altitude and speed a sudden trim change, and / or aileron damage could cause a major upset which would be difficult if not impossible to recover with a damaged stab