2 weeks, 140ish Wyverns, 5 Pillars, 4 Storm Callers, a dozen rare gears later. I FINALLY GOT THE LEG!!!
Here is my story:
I started out with tamer and did 100-odd wyverns. I recorded this based on the rare ingred each wyvern drops. Got pillars and callers, but no legs at all. As I am on Enhanced Client, I experience graphic glitches whereby some armor parts dont appear properly. I thought this to be the case as well for the legs, and I had physically mouse over the first 20 grids on the corpses JUST to be sure.
Then, out of despair, I switched out to fighter, hoping the bushido honor luck would help. Got a Caller on the 2nd wyvern, so hey, it might just work... the next 30 or so wyverns bagged me another Pillar. Then I switched to Legacy Container view in the EC. After like 480 diligence essences and faery dusts, I stopped looting and just skim to pop the wyvern as soon as possible.
Just when I complained to Thunderz about my string of bad luck, the brown plate leggings finally appeared on the wyvern that killed me...
For those that are still on it, don't give up! I was about to, but gritted my teeth, and persevered. I suppose Im one of those RL bad-lucked person that took so long to pop a leg. You might have better luck! Keep at it : )