Currently using a +3 Polehammer and have bonked quite a few people with it.
It feels awful.
As it stands, there's no redeeming feature for the polehammer.
It has worse damage than you'd think, even if it had decent speed, it takes a LOT of hits to kill someone.
It's closest comparison is the German poleaxe.
Take note that when compared to aforementioned non-overpowered weapon, it does worse swing damage even at high armor values, has considerably worse speed, is (marginally) shorter, does not have bonus vs shield, has a worse stab. Furthermore the German poleaxe's secondary mode is better than both modes of the Polehammer.
The tradeoff for this is that the polehammer can technically knock down opponents. At the time of this post I am on a 20+ hit streak of not knocking any opponents down, at 7 power strike.
Finally the Polehammer only gains +2 damage to each swing at masterwork.
Admittedly at +3, it does 37p in secondary mode, which is reasonably high.
But the Polehammer's pierce mode compared to the Bec De Corbin is garbage.
3 Less speed and 2 less stab damage for 10 length and one swing damage? Yuck.
The only reason to use the Polehammer is for novelty purposes.
It could easily receive any number of buffs to both speed and damage.
Plancion for comparison is a straight upgrade to polehammer and is still weak. Still quite seriously underpowered versus the multitude of cut damage alternatives.
While I've never been a fan of using unbalanced weapons, the two handed warhammer is looking very appealing. That's the kind of speed and damage a top-cost blunt weapon should have, obviously the polehammer would need to have adjusted stats because it isn't unbalanced. But wow, 5 more speed, 1 swing damage, 1 stab damage and an additional 1 swing damage sounds fearsome, maybe even viable.
Cut meta is boring, especially when there's no viable blunt options and only one viable pierce option.
And when the polehammer is compared to said cut polearms like German Poleaxe and Elegant poleaxes, its quite obvious how absolutely garbage this weapon is - weaker swings, slower, worse stab, the list goes on.
Just make it powerful enough to feel good when you've equipped it. Hitting someone 5 times with no knockdown then dying to 3 hits from a faster cut weapon (both users at 55+ body armor) is pretty frustrating. It genuinely feels underpowered and it's always surprising when you actually manage to kill someone with such a weapon that has these horrible stat budgets.