While delving through this site i have seen a few times that people believe that Hoid used the bead of Lerasium with other metals in order to make himself a misting. However I believe that I have proof that he used the bead to become a full Mistborn. Before I go into this, my proof is based on Brandon Sanderson replying to this question.
I'm pretty sure Slowswift is Hoid in Hero of Ages. The Ars Arcanum says he "bears a striking resemblance to a storyteller", which I take to mean Hoid.
Hoid appears in that same chapter, but Vin doesn't meet him. Something he does spooks her. She's just too darn observant for her own good.
Here is where I got it from
If you go back and read chapter 27 in Hero of Ages, you will see that after Vin leaves Slowswifts's manor, she is followed by a Mistborn that suddenly disappears and she believes to be the Mistspirit, but because it is burning Steel distinctly, and the Mistspirit has a random beat when she burns bronze, we can assume it isn't the Mistspirit. I don't think we ever found out the identity of the Mistborn which leads me to believe that this was indeed Hoid.
But why this confirms that Hoid was a Mistborn as opposed to a misting. Hoid was definetly burning Copper here but Vin was still able to pick up on his Burning. However, if he was planning to become a Misting why would he choose Copper as an ability. It would only be useful on Scadrial so I don't think that Hoid would waste his time on picking up this ability.
Please comment what you think of this theory.