I agree, they are lacking in spears. You have to use city Spear Militia for a long, long time. Those are weak in the mid game, and tend to die fast. Armor upgrades only helps them so much.

There is a two-handed axeman. That is the Norse Axeman. 17 attack, armor-piercing of course. These guys are wicked evil in a flank attack.

Later on, you are correct in that many ways you are relegated to using stock Catholic faction units. But I still prefer keeping Axemen and Huscarls around. There are more opportunities for their axes to do a lot of damage as the level of armor goes up, and it's just awesome to watch seige towers dropping a horde of screaming viking axe-wielding maniacs on a wall.