If you're hoping to do arenas, first a few gear changes:
-You need Spidersilk Drape. +4 Hit is ridiculously helpful.
-Get +mp5 enchants on Inferno Robe. Personally I think 5mp5 is best for bracers as well, but Spell Power is fine too.
-Your +Int weapon set up should not be Stam-based - it should be Int based! Get a Twisted Chanter's or that silly BoA staff.
Now for the build...
-Jewelcrafting? You'd be much better off with Engineering if you want things to tinker with in WSG. If you're going to be doing a lot of arenas, go Mining or Skinning (Mining is probably more 'sound.')
-Undeads are probably the worst race now, so I'd highly suggest you go BE. They're amazing in 2s and a great help on O. WotF shares a CD (sort of) with Trinket now, remember.
-Shadow doesn't work. Priests are not good burst/damage classes, there's no argument about it. Wanding is the (good) priest's predominant damage-dealer, and you'll be better off putting your points in ways that will help you (and others) Not Die. The difference between a 2.5 sec heal and a 3.0 sec heal is just incredible.
Disc used to be a viable spec (RIP Improved Wanding...) but it's just bad too now. 0/10/0 is accepted to be the best.
Think about how you're spending your talents. 10% more shadow spell damage? Sure, it's a bonus I guess, but what does that mean? Your Mind Blasts will hit a little harder? Having your DoT tick a little bit more is rarely very useful; the main purpose of the dot is to discourage bandaging - now, of course the damage is relevant and useful, but adding 10% is just...barely noticeable. As for the other talent, that's just completely useless. Get a Spidersilk Drape and don't worry about Hit. And what's 6% mana off of...what, 90? 5 mana per SW
is just nothing.