[Highborne]

The biggest complaint I have is no Rage skills and no leveling until 2nd island, it is lame and boring. Also, as you pointed out the Viking class is screwed over pretty hard by this.
Easy fix would be allow all the other Rage skills that can be learned except Valk and level as normal (think about it, your first Rage skill is you attacking the enemy...how is that NOT leveling by using it). So the Ice Wall, Ice Attack should be able to be learned and leveled before meeting Valk #1.

I think there is some variety of units on the first four islands, but it is limit to primarily vikings because the rest just don't have the numbers to support playing with them unless you are amazingly good at a no-loss scenario (Dwarves, Plants, Bears (all versions)/Snakes/Fish/Wolves/Spiders, minor Undead (from a boat iirc), Pirates/Marauders, a few Trolls and Jotuns). However, besides running maybe a Jotun, Pirates/Mauraders and Bears the rest are in so little numbers...it isn't feasible to even attempt armies other than vikings.

Finally, Rune Mages are ridiculously overpowered. Just saying.

And yes, lack of Regalia...I have found maybe 4 (including Dragon Gem for 200k) and I dunno if I will ever be able to upgrade my valk to level 5.