Well gemming is spot on for your muti spec... gem either haste or AP/haste while keep the hit there but itemization for muti makes that hit hardly a problem. So fine there.
Try to get the tier gloves and ditch the shoulders for the deatwhisper-25 shoulders if you can. Bracers from sindra-10 heroic could be an upgrade in order to ditch a bit of that Arp. Also try and get geistlords punishment sack and try to get ikfirus. As that would boost other stats and drop Arp a bit more. My thought a bit but of course if you disagree send me a pm cuz I might be wrong in my assumptions.
Well I can not link but My Char is: EU-Kul Tiras - Xirthill or click my signature :-)
Cheers