The gear for the most part is alright. You are still reforging to hit over the 7.5% cap so that can be fixed but not terrible overall.
I went ahead and looked up logs for your guild and....wow. Well I do think you need to start from the beginning and reread all the beginner guides for the class. I will be using your Magaera 10m kill logs, which you can kiss your healers asses for carrying the crap out of you btw, (found via WoL:
http://worldoflogs.com/reports/grx2g...?s=8794&e=9249) as the example as you are pretty much always tanking something. I am going to be blunt with you here because you are in need of some work. Hopefully you do not take it as an insult because it is not but I am being honest because from what I am seeing in the logs is that you are being carried by your healers. Please note that its NOT RNG that is making you take a lot of damage. It is you ignoring the core mechanics of the class you are playing.
You hit shield block 0 times and you hit shield barrier 12 times in a 7:34 fight. This is completely unacceptable at your current gear level. You spent ALL of your rage (that is used now as active mitigation and not dmg as previous expansions) on heroic strike.
You used heroic strike 77 times! That is WAY too much. 15 of those were free through ultimatum procs so that means you spent 62x30 1860 rage on heroic strike that should be used to take less damage (especially with your ilvl, whereas higher ilvl may be granted more leeway in mitigation vs dmg). You really should not be using heroic strike outside of ultimatum procs because that rage is better put to use through block/barrier.
I am going to use just block here as an example because it has less variables than your specific barriers due to vengeance and rage costs ranging 20-60 rage. In this fight you should be using a mix of both barrier and a few blocks because there are both magical and physical dmg but that is beside the point. 1860 rage is 31 shield blocks worth of rage. It is 186 seconds worth of 30% less physical dmg taken with the chance with the chance of 60% through crit blocking. Also note that critical blocks enrage you and will generate 10 rage so keeping shield block up more often will actually increase rage generation along with a minor damage increase (10%) while enraged.
You will also note that you used shield wall/last stand once. You will also see that you took enraged regen (I personally would go with Impending Victory but to each their own) and you only used that 2 times. Shield wall/last stand could be used more in a 7:34 fight if planned out so they are up near the end where you take the most dmg. I know the damage in this fight ramps up but saving your healers a little extra mana in the beginning is always a plus. Enraged regen is a 1 minute cooldown and not a very good "oh shit" button so it should be used as much as possible to get the full benefit from it.
Taking a quick look through your longest Ji-Kun attempt I also see 7 barrier and 0 blocks in a 7:28 fight. Granted there is tank swapping here but 0 blocks is absolutely unacceptable as a tank on this fight. You seem to have somehow skipped over the core mechanics of warrior tanking (block/barrier) along the way and you need to go back and start over as far as warrior tanking 101 goes. Heroic strike is not the rage dump it used to be.
On a side note I do not see any use of tier 4 and 6 talents (should be dragon's roar/bloodbath for these fights) and no use of shattering throw. Banners I do not think show up in logs so make sure you are using those as well (demo/skull).
I hope this helps you out and if you have any other questions let me know. Also keep in mind that just linking armory rarely tells the whole story. Posting logs is the best way to take a look through and see exactly what is going on. Good luck!