FINALLY!  I did it! I beat schtupid Gao Ren!!  Not only did I finish the quest but I *killed* him in one go! YESH!

I think my problem was that I went with everyone's suggestions to use a hammer against him and well, to be honest, I kinda suck at hammers.  

So instead I rethunk my strategy completely.  I pulled out all the stops and stocked up on large/bounce bombs, fitted my armor with bombardier jewels and switched back to my WoC: long sword, and proceeded to slice him to ribbons and bomb his ass. Not only was I more accurate, but I took much less damage because I was more fleet on my feet.  I also found out from watching Nico Nico Douga that you can trigger the dragon skewer spike wall thing more than once-- You can do it once per 10 minutes.  I wish someone had told me that earlier!

Man I feel so relieved now that he's out of the way.  He was definitely a wall for me and I think he kinda traumatized me for a while.  But now I can finally move on to the upper ranked elders. Yay! Go me!  I'm unstoppable now!