You realize Viking in FF is just another form of Warrior right? Why else would Warrior have berserk as a skill?
If you need to make a class/job with a two handed hammer, must it be so uninspired that the best one can come up with is an already existing jobs theme? In this game we already have Nero and Grynewaht using two handed hammers setting a precedent for an existing class/ job of Garlean origin. From my perspective they do not seem to be Vikings to me. Would it not make more sense to have a Engineer who makes magitek field emitters that create defensive/ buffing AoE's and make it a Tank role? Something that would mirror Machinist but with a defense role rather than a DPS. The whole story could be wrapped around Garlean defectors trying to help make their homeland something to be proud of, something i feel is being missed with the current defectors we have had contact with.
He even calls his hammer Mjolnir ffs...
https://vignette.wikia.nocookie.net/...20130818075023