Can not sheath means if you try and put it on your back or use anything else, it will drop to the ground.
Currently my poleaxe build used to use a German Poleaxe and that was nice for cramped sieges, but I switched to using the Standard Poleaxe after a reccomendation and I have been doing amazingly well with it in almost any situation.
My current build I changed my mind and only have 66 wpf on olearms and 127 wasted on 2 hander (since I changed my mind), but I still do very well with it, so I suggest the following:
Level: 30
Strength: 24
Agility: 15
Converted: 8?
HP: 69
Power Strike: 8
Iron Flesh: 5
Athletics: 5
Weapon Master: 5
All wpf goes into Polearm (should give you about 140-ish say 149?)
My gear (which is sustainable and over the long run gives me money):
Poleaxe
Barbutte
Black Coat of Plates
Wisby Gauntlets
Light Strange Boots
So about 36K total in cost.
I hope that helps!
EDIT: The Swiss Halberd I do not like, as it can only overhead or thrust, no side swings.