Heya, I'm a warrior tank in a guild that is working on clearing Ulduar (25-man) and have everything cleared up to and including Hodir.
I'm one of the off tanks in the guild. I don't have a problem with this, because my gear is behind our main tank's, who also happens to be a druid with 10k HP more than me buffed and ~10% more avoidance...
Anyhow, I've been having some real trouble lately with, well, staying alive. I feel that my gear is getting pretty strong but my survivability is not matching it. Today, for instance, I was the secondary tank for Kologarn and I got killed 2 times while tanking him, causing 2 wipes. And after we downed him, we went to Iron Council where I died another 2 times while tanking Runemaster, causing another 2 wipes and forcing the raid leaders to switch up some assignments

I really think sometimes that I must be just having some terrible luck, because how could a stinking off mob from Iron Council be owning me like that?
To be honest, I was embarassed. Like I said, I feel that my gear is pretty strong and my talents are good, but my survivability is just crappy at times. I understand that I have a few weak points in my gear setup, but here's my armory:
The World of Warcraft Armory
If some of you could maybe point out some gem changes, talent changes, or key pieces of gear I should aim for, that'd be great. I guess I'm looking for a tanking Report Card, heh.
Oh and as far as keeping debuffs up, using shield block, and popping trinkets, I try and keep a solid rotation and trinkets and shield block are always on cooldown. I'm not just sitting there hoping my gear does all the work
Thanks in advance for any helpful info.