Defense is also avoidance; the UBW sports more than 1% total avoidance (not including block. never including block >:| ) from defense and the cleaver only has 0.85% total avoidance from the parry
armor is mitigating damage all the time as opposed to the parry and this weapon adds significantly to your effective health to boot.
on another, more... hilarious note:
some argue until they are blue in the face that parry is a "threat" stat because of the potential speed increase from parrying an attack.

its not a threat stat and you shouldnt ever think that. there IS a potential threat gain from parry but it is so minute that i dont think it is even worth taking into account.