Since you say it's not Northworld, it sounds to me like The Hammer of the Sun, third book of Michael Scott Rohan's The Winter of the World trilogy. It's set in a magitek civilization during the last ice age; the duergar later degenerated into what we know as Neanderthals.
The story is implied to be the basis of Finnish and Norse mythology especially (though not exclusively): the hero's girlfriend is a Valkyrie, but in service to Louhi (who's lots better looking than in the myths) rather than Odin -- who's named Raven, here. Also, the hero, Elof Valantor, is the inspiration not only for the Daedalus, Vulcan, Ilmarinen, Wayland, and Volund myths, but also for Thor -- you do NOT want to get hit with his hammer, particularly when he ... well, I'll let you read that for yourself.
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Big Brother is watching you. And damn, you are so bloody BORING.
The story is implied to be the basis of Finnish and Norse mythology especially (though not exclusively): the hero's girlfriend is a Valkyrie, but in service to Louhi (who's lots better looking than in the myths) rather than Odin -- who's named Raven, here. Also, the hero, Elof Valantor, is the inspiration not only for the Daedalus, Vulcan, Ilmarinen, Wayland, and Volund myths, but also for Thor -- you do NOT want to get hit with his hammer, particularly when he ... well, I'll let you read that for yourself.
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Big Brother is watching you. And damn, you are so bloody BORING.