coinbinder the awakener

if the topic above does not interest you, try this. Why is metal so important? Is it somehow connected to life in the Cosmere? When Kelsier held the shard of Preservation, he saw people as he did metal. It happened again when Wax held the bands of mourning. To his eyes, metal and the souls of men were the same thing. Is this hint BS gave us just for Scadrial? Or the entire Cosmere? Nightblood is the equivalent of a shardblade, but what if the bands of mourning are the misborn version? They are all made of metal.

So first off, lets talk about the chosen of the shards. I do not mean just people who can use in vesture, because the shards don't always consciously choose them. I'm talking about the next level of magic users... And so far, that consists of the Returned(Warbreaker) and the Heralds(StormLight). we know these guys were conscious decisions because Honor refers to them as "My heralds" and Lightsong remembers Endowment giving him life. So the question remains... What exactly are the Heralds and Returned? How do they differ from other magic Users?