Not sure if you have changed your gear already or if running heroics has gotten any easier, but ill post my advice anyways.
I have a prot pally almost equally geared, though perhaps gemmed a bit better and my talents differ and who knows perhaps gameplay.
About your gear:
It isnt bad at all, it is just lacking a few things or some things could be adjusted.
Yuo have 0 spelldmg on gear. Now only up in t5/6 content we might need some extra spelldmg on gear, but untill then we only need some decent spelldamage on the weapon. 130+ with +40spelldmg and perhaps some oils. Spelldmg is THE way to build agro, of course you are using conc. HS, AS, SoR/JoR/SoV, but having +spelldmg will greatly improve your threat. Conclusion drop the defense 1h, get a s2 pvp mace(PVP) or crystf. sword(AH) or cont. blade (CoT rep) and enchant it.
Your ring doesnt add up, its a healer ring. Get a defense one, high stam some agi some +defense/dodge/br or even blockvalue. (eg. Andoru's Tear, questline CoT/Black Morass or delicate etherium ring (AH, boe)
Pants arent bad, could be better imo. Timewarden's Leggings (CoT rep)
Bracers don't do anything for you as a tank now except the stam perhaps so this could be upgraded.
Neck, although not bad stam and the res does help somewhat in tanking, it isnt the best stat to increase, i suggest easy to get Strength of the untamed (CE rep)
The Libram isnt for tanking, get the badge reward libram of repentance.
Now the gems, seeying as you have an nice amount of defense and are looking into doing heroics, you could opt for change in gems, take out the +dodge/+def+stam and get pure +stam (+12's). Of course you will want to keep the 485 minimum for uncrit in heroics and perhaps your avoidance will drop somewhat, but in general you should come out ahead to run heroics a bit easier and then upgrade that avoidance even more. (with holy shield 102.4%)
Talents arent bad and should do fine, personal preference is to get the 5/5 ardent def. I even dropped reckoning, though im not sure if that is a good thing, it just seems that my threat hasnt suffered and i got more valueble talents in exchange. (5/5 ardent and impr judgement)
About gameplay/skills. Try to always have holy shield up, always righteous fury up, use aura that is usefull. I used to run with ret aura but noticed that it is only usefull if you are aoe tanking, same goes for blessing of sanc. Usually have kings on yourselv and salv on the rest. In general, use SoR on mobs and SoV on bosses, judge when ya can.
Concecration is a mana eater, but if you are getting good heals you can use it quite a lot. Is it needed? Hardly, but it does add some threat.
I seem to be doing heroics fine in similar gear. SP, Mech, BF, Ramp, BM, Shett, UB, Those should be doable at least.
Good luck