It is said in HoA that many Bronze mistings were Savants simply due to the sheer volume of time they were burning Bronze. I suspect Vin was a Bronze savant. I asked Brandon once if the reason she got spooked off by Hoid was that she was detecting Hoid using a different form of Investiture with her Bronze, he smiled wide and started to answer but ultimately RAFO'd me. Obviously she was also augmented by her Bronze Spike, but I suspect it was both that and her being a Bronze Savant.