As far as gemming/enchanting goes, I'd probably hit the +9 stam bonus in your belt with a 10agi/15stam gem in the red socket and change the shield enchant to 18 stam, but other than that your gemming/enchanting looks flawless to me.
As far as gearing goes, I would start working towards the 2pc bonus and getting that in the helm/shoulders, but really you're going to just be gaining the 2pc bonus, the difference in stats is negligible if not a downgrade from what you have if you are using 264 gear. It looks like you've bought everything you can with frost emblems, maybe start selling orbs if you're not going for T10? lol. The T10277 gear is very good, so if you will have access to that then it may be worth it to start collecting, especially if you don't need money.
Your armory looks pretty solid to me though, keep up the good work
Oh one more thing, switch out harbinger's band with clutch of fortitude or (if you have it) H-Band of the Twin Valks. Both of those, especially the H-BotTV are actually more physical EHP than the harbinger ring. For LDW and Sindragosa probably put on Harbinger's, but otherwise it's really a pretty terrible ring.
The only other upgrades you can get are raid drops so... ya, kudos to you, and your weapon is fine. Rock on and go destroy some content!