I have to agree, that stun is a bit all over the place.
Also, I'm not biased towards polearms, but I use the Elegant Poleaxe since July, and in duels the stun can give you just enough time to go for the killing blow.
Maybe I'm alone with this, but most of the time when I see the stun, (In the heat of a duel it's not working all the time, sob) I either move back, or just feint that "could kill you" attack.
Dunno if we ever see something happen about this though.