Normally you are able to feint with unbalanced weapons if you "feint" at the very start of the chamber-animation...
Could be your doing it to late? Or chadz has nerf your playstyle
weapon length: 96
weight: 4.5
difficulty: 15
speed rating: 92
weapon length: 96
thrust damage: 0 blunt
swing damage: 35 blunt
slots: 2
Can't use on horseback
Unbalanced
Knockdown
This "Unbalanced" may be your problem unbalance weapons cannot cancel there attack as quick as balance weapons
Here a Wiki link for more info
When you swing an Unbalanced weapon and miss (not hitting an enemy body / shield / block) it needs more time to chamber it again.
http://wiki.c-rpg.net/index.php?title=Unbalanced
If you see the term unbalanced you will also take longer to regain balance after attacking and its tough to switch from an attack into a block at speed.
http://www.alteredgamer.com/mount-and-blade-warband/69406-warband-weapons-guide/
Shoulda gotten an authenticator.
I will log on in a bit to test this myself, I would be mad if I am not able to feint with my bar mace