I'm not sure if they're planning to add more weapons, but I know there's mods that add weapons. I don't have any experience with those so I'm not sure if a 2-handed sword is included among them. For the latter, assuming you're not opposed to mods, More Gates on NexusMods adds two drawbridges in addition to the extra gates, doors, and windows. As always, use mods at your own risk, but they could provide you what you're looking for.

Vikings didn't have bihanders, as these were introduced pretty late, at a time when gunpowder already was invented. Even their predecessors, the one-and-a-halfhanders were classic weapons of late-medieval knights in full plate armor.

They only make sense in that scenario, as you wouldn't need a shield to block incoming attacks. The bihanders themselves were a VERY special scenario as these were used to hack at incoming long lances. Very dangerous, so these guys were payed double the usual fee, hence them being called "Doppelsöldner".

You are trying to create a scenario that was several hundred years in the future of typical Vikings.