Viking metal is not a genre. It's a lyrical topic. The closest thing there is to "viking metal" is black metal with Scandinavian folk bits. Most of which sucks.
Hammerheart is most definitely not 'black metal with Scandinavian folk bits.' It is THE viking metal sound. Same with a band like Moonsorrow or Falkenbach and some others.
I take Mort to be defending the term "viking metal" as marking a discrete genre of metal. I'm inclined to agree, although I know the evidence otherwise is quite convincing.
Most metal that attempts to qualify itself as viking metal ends up being something that can simply be redescribed as folk metal; however, I'm still somewhat convinced that certain examples fall somewhere between what I would call simply folk metal or black metal, and I want to try and see if I can delineate the elusive genre they fall under. Mort, perhaps you'll want to assist (if you even agree with what I'm saying).
I think that folk metal constitutes a faster, more lively song structure than what I would consider to be viking metal. I've always believed that viking metal incorporates a doom influence; Bathory does this on
Hammerheart and the
Nordland albums, but it's truly illuminated and expounded upon by Ereb Altor. Thyrfing employs the full doom influence on
Vansinnesvisor, which I believe is a viking metal album. I also think of Einherjar as viking metal (or at least their album
Blot). Moonsorrow employ similar song structures as well.
EDIT: Mort, you mentioned Falkenbach, which I would agree with and add Doomsword.
Hammerheart is crappy Manowar worship. It's traditional/power. Don't feel like listening to those others, but if they sound like the relevant Bathory albums, they're probably traditional/power too.
I can't express in words how dumb this comment is.