But her earring, which enable her to repel the mists, does suggest hemalurgy. It also prevents her from burning the mists, as the only time she does is when the Lord Ruler pushes it out of her ear.
I think all the inquisitors have allomancy and hemalurgy. I think they get allomancy from that metal that Elend ate, and then Hemalurgy does something else, like give them their increaced healing, perhaps some of the spikes enhance natural abilities, speed, strenght, maybe ONE spike enhances allomancy. Maybe other spikes give the inquisitors their extended liife span. I think it's something like that, each spike bestowing some sort of ability, which would also explain Alendi's prowess, he probably had enhanced strength or speed or something from his piercings.
I think Vin's ability to pierce copper clouds may be due to hemalurgy, but she also has many other abilities that suggest she is special on her own. Her quick grasp of allomancy, her extreme subtelty with soothing and rioting, her ability to match kelsier's steel push, even though he should have easily overwhelmedher because he is heavier, and of course, her ability to burn the mists. The earring is special, but Vin is also special without it.