For the Crystallized Firestone, upgrading your weapon would make sense if there is no chance of progressing through Heroic Beth anytime soon. The neck piece would be the best option otherwise as it is BiS when upgraded and offers a larger stat increase then the range weapon.
You would be better off using the block meta gem, it reduces more damage then the armor one.
Your Dodge and Parry are way out of sync, that means you are taking a much larger toll from DR then need be.
Until you cap your CTC you want to use 2 mastery trinkets, the Essence of the Eternal Flame from the FLs rep is a good option as is the Mirror from the TB rep.
The tanking cloak from the thrall quest line is better then your current one.
You can gain more mastery by reforging the parry on your Chest and Wrist pieces into Mastery.
You should be using the Parry/Mastery red gems not Parry/Stamina.
You should be using the Mastery/Stam blue gems, not pure Stamina.
Your JC gems should be pure Mastery.
The talents Gag Order, Blood Craze and to a lesser extent Improved Revenge are not worthwhile.
Picking up Cruelty/War Academy/Deep Wounds would get you a large DPS bump.
For single target boss fights, revenge is currently not of much use, you'll get more out of your rage if you favor devastate over it.
Hope that helps.