Platinum Shield of the Valorous – Shadow Labs
Ogri'la Aegis – Orgri'la faction
Aegis of the Sunbird – Botanica
Crest of the Sha'tar – Sha'Tar faction
Shield of Impenetrable Darkness – Nightbane in Kara
Bulwark of the Amani Empire - Jan'Alai in Zul'Aman
Aldori Legacy Defender – Gruul
Kaz'rogal's Hardened Heart – Kaz'rogal in Mount Hyjal
Bulwark of Azzinoth – Illidan in Black Temple
As you can see, there are four shields initially available to the protection spec warrior when turning 70. These can be picked up relatively easily by grinding instances or faction reputation. They offer "good enough" stats to get the warrior through the first tier of end game content, and won't really degrade the tanks performance through encounters up to Mags.
However, after T4, a problem appears. There is quite literally no shield that drops for a tank in any T5 instance. Tanks have to be lucky enough to get the shield off of Gruul or Jan'alai to drop for them. This in itself is a problem, since guilds usually do not run Gruul that often once they've killed him.
It is often times that a tank will end up doing most of SSC and TK with either the shield they got from Sha'Tar rep grinding or from Nightbane in Kara. Worse things have happened, that's for sure, but eventually all of the other tanking gear will be upgraded, except the shield. When that happens the shield becomes a bad shield for the warrior, and causes problems for him. It provides less stats than necessary, and does less threat than necessary – all the while DPS is increasing and bosses are hitting harder.
It is quite possible for a tank to go through killing Vashj, Kael'Thas, and everything up to Kaz'rogal with a shield that is a full 41 item levels less than the rest of his gear. This is the point where a tanks shield becomes a liability, and needs to be replaced in short order. I have heard first-hand accounts of tanks having awful luck and making it as far as the Illidari Council with the Crest of the Sha'Tar.
Fortunately, for the tanks lucky enough to make it to the tier 6 instances (and get lucky with a drop or two), options quickly become available from Kazrogal and Illidan. But the journey from Kara and Gruul, to Kaz and Illidan, can often times take the better part of a year – if not more. During that journey the shield's utility steadily decreases until it becomes almost worthless.
What can be done about this? Well, besides Blizzard putting in a few new shields in the game at the tier 5 level, the tank has to become proficient with mastering their skill rotation. Threat output from abilities that do not rely on the shield have to be learned the hard way, and classes often times find themselves threat capped from an equally geared tank.
How do you cope with the lack of adequate T5 shields?
*I'm not including PvP shield since they don't offer correct itemization for PvE, which is what this article is about.