As we all know. 2 handed weapons in this game are generally bad.
General status
There's a moment in the early game where stagbreaker is quite good in the sunken crypts but that's about it.
The iron sledge is a huge iron cost. And a 1 handed mace is nearly as good in damage (frostner, iron or porcupine) and definitely better in DPS.
I've just tried the mistlands 2 handed sword (Krom) and the dual knives and was surprised at how weak they were.
Suggestion
Replace the polearm skill with spears and a 2 handed weapons skill for all 2 handed weapons.
Every 2 handed weapons damage will be amplified by the weapon type skill (sword, knife, spear, mace) AND another skill for 2 handed weapons.
If you skill everything to 100 this effectively doubles the damage of the 2 handed weapons. Which they desperately need.
Also doesn't make them too powerful in the early game because you wouldn't have a high skill level.
Also let's to switch from stagbreaker to Krom and get the skill boost.
The atgeirs become 2 handed spears so your spear skill translates to the later game. And spears are also weak.
Attacking with a 2 handed weapons would skill both your 2 handed weapons skill and the primary skill.
Source: https://www.reddit.com/r/valheim/comments/11vxtnj/2_handed_weapons_suggestion/