as i've mentioned in other threads i think that Alendi is a hemallurgist. i think it would be an interesting parallel between him and Vin. from what Kwann said it seems that the piercings were a necessary part of being the Hero.
we do not know the manner in which Alendi recieved his piercing.
i think we can actually assume that they were given to him after people began to believe he was the Hero. i think it mentions them as the "piercings of the Hero" as if there were something to differentiate them from other, more mundane piercings like those of the terrisman or from any piercings that Alendi may have had before becoming the Hero. so i think Alendi's a hemallurgist. to what degree is unclear. for example Vin is certainly less hemallurgic than the inqs but i get the feeling that Alendi parallels Vin and is hemallurgic in a similar fashion.