It doesn't have to be set in the forzen north. Maybe it could have an island theme with britan, scotland (kilt armor for warriors

To make things more interesting, you would have to pick which side you were going to be a part of from the very beginning and each side would have seperate starter areas and trainers. Perpahs with different skills so a viking warrior would have a slightly different skill set than an scotish one.
Classes which could work
Druid (part ranger, part monk, might have spells that are weather related)
Berserker warrior (two handed swords and axes)
Storm caller (like a warrior version of elementalists;half their ranged elemental spells are ade based).
Other things: Ships and navel combat could be added. If you have a ship you can make raids against the other nation or get to the islands to gain control over them for your side.
IMO if it is a pvp focused chapter, let side faction be less important or non-existant in this one.