You could probably tank all of Karazhan with that gear....only hard bosses in there for you would be Prince and Nightbane because your avoidance is a bit low. A few upgrades will help you out a lot.
Go for [item]Girdle of the Fearless[/item] and [item]Ring of the Stalwart Protector[/item] from the 2.4 badge vendor. The Girdle will be especially good for you because you have all that hit rating and expertise, and right now you have no hit rating and low expertise, so threat should be a little bit easier with that. I suggest getting the Ring first, though. That's going to give you a better avoidance boost. [item]Bracers of the Ancient Phalanx[/item] is going to help you out with threat as well. I think it's slightly better than the Vambraces of Courage.
Lose the +18 stam and +20 resilience glyph on your helm and get [item]Glyph of the Defender[/item] (get the KoT rep if you do not have it). Also, work for exalted Scryer reputation for the stronger shoulder glyph.
All the other obvious upgrades (helm, boots, shoulders, weapon) come from Karazhan drops, so you just gotta get lucky with the drops!