A common enchant

Everytime I see a tank sporting Armsman, which is like 99% of the people on my server, I always end up shaking my head in disbelief. Let's look at the enchant more carefully, shall we?

Enchant Gloves - Armsman 5 sec cast
Permanently enchant gloves to increase threat caused by 2% and increase parry rating by 10. Requires a level 60 or higher item.

Now, 10 parry rating is roughly 0.22% parry, but when you factor in diminishing returns, its true value would be something closer to 0.1% parry. But I'm sure that's not why most tanks pick it up. They are enthralled by the 2% threat increase. Now, think about it carefully. On a 7 minute boss fight, an average tank can put out 2 million threat. 2% of that is 40,000 threat. That's barely more than 2 Shield Slams + autoattacks + 3 or 4 Heroic Strikes. Not convinced? Let's analyse what happens in a heroic. On average, mobs in heroic instances die before the tank has 50k threat. 2% of 50k, therefore, would be 1000 threat. That's even less than one Devastate!

Comparing to other alternatives - Heavy Borean Armor Kit for Effective Health and Precise Strikes and Expertise for threat; 18 Stam equates to roughly 210 HP with Vitality and Blessing of Kings, and you already know how good hit and expertise are for threat, and in expertise's case, survivability.

Need I say anymore?