I belong to a lineage of vikings. Some of my great-great-great etc. ancestors could duel wield claymores, with relative ease. And being ambidextrous has been in my family since forever. With a little practice (And plenty of strength, though not superhuman) plenty of people could duel wield big swords. If they were ambidextrous anyways.
Ummm .... you need to research your ancestors a little better
Claymores are Scottish, not Norse, and came about 400 years after the Viking age. Most Vikings used axes - big ones granted, but only one at a time. Viking swords (circa 900 AD) were generally broader, shorter,and somewhat lighter (about 2-3 lbs - see Oakeschott Type X and XI) than the standard medieval long swords that followed circa 1100 AD (about 3-3.5 lbs see Oakeschott Type X II).
It's out there on the net if you really want to learn.
I like the idea of sinking with metal armor or too much weight. Another incentive to travel light. For me the added realism is about improving game play and not taking away from it. I like the idea of being forced to make hard choices like abandoning my loot to run away faster.
As for the title, leave dual wielding two handers to a mod for those who want it. IMHO it would look silly in the game. If others want to mod it in then that's what mods are all about.