So one thing that I think would make Parry a more viable stat would be to add a counter attack trait to it. While still it would be a chance reaction, it would increase it's value quite a bit if each parry not only reduced damage, but inflicted damage as well.
I suppose if you wanted to flavor it up a bit more, you could do things like...
Give Drk's Magic Parry, which could allow Drk's a chance to parry magic attacks and cause MP drain based of % mitigated.
Give Pld's Tactical Parry, which parried attacks will reduce mob damage out for x-seconds.
Give War's Intimidation Parry, which parried attacks increase crits for x-seconds.
If your going to make a stat so chanced based, then the reward needs to match the rarity of the chance. I feel with the right modifications, Parry could be stat worth bothering with, but I do think that countering attacks/reflecting damage could be a way to go about it.