Well, if you're asking for suggestions, I suppose something we might need to know about the setting is what kind of world we're going to be in. Excuse me while I get verbose; [i]Ahem.[/i]

Where are we? An endless desert, given shade only by clouds and nightfall? Or a forest, of verdant green and unknowable depths? And from the where, we need a when. Are we in the midst of a war, battle breaking out at any moment? Has a princess just ascended the throne, and marked an era of peace and prosperity for her Empire?

You mention a Devil of some sort, a Dark One who represents evil above all else. So what is its opposite? What higher powers do the people of this world believe in? Is there only one belief, or many? And what magical creatures are to be found? Will you only be including evil ones, or will there be neutral and benevolent ones as well? My knowledge of Scandinavian folklore and myths is sparse, but I know a few - valravn, nisse, nix, and how trolls were actually rather human-like, and that the Dutch troll was actually quite kind-hearted.

...I'll stop now. Out of the kindness of my heart, so that I don't lecture you about the many things to remember about writing that you assuredly already know. Not because it's 11pm for me and I'm getting tired.