the weapon glaive has the weapon group "Pole Arms"
but the glaive-guisarme has "Polearms".
as i understand it they should have the same weapon group.
okay, the problem exist for most polearms
tiger fork, glaive, guisarme, halberd, ranseur, bardiche, monk's spade and nodachi have the group "Pole Arms"
hooked lance, horsechopper, bill, glaive-guisarme, bec de corbin, lucerne hammer, ogre hook and naginata have the group "Polearms"
ultimate equipment, version 6.07.00