Hey guys long time lurker but I got this theory and had to test it out to the community. There are spoilers to Shadows of Self. The spike used by Bleeder is described as long as a finger, silvery with bits of red like rust. Now Sazed aka Harmony knows atium so it's not that. We have WoB stating Odium has plans for Harmony I think that the metal is a manifestation of his Investiture just like on Roshar he has spren. The only link I have are the bits of red, Odium seems to have red investiture. So what is Odium planning if that is his attack? Only another shard can interfere as MeLaan says the kandra are frightened.