Yeah, when in polearm mode it uses pole arm wpf.
I love the longsword for being so ridiculously versatile.
2h, 1h + shield (with penalty), Halfsword as pole-arm with lowered range, Halfsword as a 1handed spear w/shield (totally lollable wtf). 4 weapon modes. Although the last one shouldn't be possible, it isn't OP in game to my knowledge.