Thanks for the question. You're definitely right that the concept of Death is a complex one, and that its perception varies from culture to culture.
From the perspective of the main characters, it's a terrifying and evil force that seeks only to inflict destruction. For the Harbingers (the cult that worships it), it brings peace and salvation. For Drovanians, Death rewards their deeds on the battlefield with honor in the next life (similar to the concept of Valhalla). And for the elves, it's a necessary cosmic force that is neither good nor bad.
I'll be going more into depth with this over the course of the story, as the main characters will be interacting with these (and other) groups of people.