I was talking to a good friend of mine the other day who just recently respeced from the classic Frost/Arcane build to a higher dps Fire/Frost build. He had been running Shattered Halls (the daily heroic) without his favorite healer (me) and was complaining that his dps was threat capped due to his lack of Salvation. He made a comment that if he continued to be threat capped in this week's upcoming raids he would switch back to the lower dps Frost/Arcane spec so that he would no longer be threat capped.
I've heard similar arguments before about switching to lower dps specs or weapons in order that one would not be threat capped and I feel that this is a logical fallacy. If someone is threat capped, that means that that person is doing the maximum amount of dps possible under the current circumstances. By switching to an inferior set up, either by switching specs or gear, you can only hurt your dps, which would be a negative outcome.
There are, however, many ways of minimizing threat while maximizing dps, and I'd like to explore them here. As a brief primer, your maximum dps is out of your hands if, and only if, you have tried all of the below threat reducing tips.
A) The must fundamental way in which a player can reduce his or her threat is by specing into talents that provide a percent threat reduction. Almost all dps trees have these talents and they should be a staple of any build. If you lack a threat reducing talent that you can obtain, please respec.
B) The most important buff a dps class can receive is Blessing of Salvation. No other buff can increase your maximum possible dps by up to 30%. If you have a Paladin in your party or raid and you do not have this buff, kindly ask for it, and, after you're done for the night, never run with that Paladin again since he or she does not understand the importance of proper blessing.
C) Tranquil Air Totem is something that you'll have to ask special permission for. If you are not in the party with a tank, then ask your Shaman about this totem if you find yourself threat capped. However, since the use of this totem means the lack of Wrath of Air, Windfury, or Grace of Air Totems, your Shaman may decide that the dps gain you receive from reduced threat is less than the dps lost by the rest of the group, who may not be threat capped and can make good use of the other air totems.
D) Some special items in the game can be used to reduce your threat, such as the Prism of Inner Calm. These items are few and far between, however, and you may not have access to one.
E) Some classes, such as the Mage, Hunter, Warlock, and Rogue have access to abilities that don't simply reduce your threat, but eliminate or cut it entirely. Proper use of these abilities should limit your threat problems and provide you with higher long term dps.
F) Some abilities, such as Heroic Strike, have uses in dps rotations, but also cause increased threat. If you find yourself using an ability that causes increased threat in your dps rotation and you are threat capped, you may wish to reevaluate your choice of abilities or simply drop the one.
G) Enchant Cloak - Subtlety. Get it. Love it.
I feel that if you have followed all of the above tips that you can, and you are still threat capped, then your maximum dps is no longer in your hands, but in the hands of your tank, who would need to increase his or her threat per second (tps) in order to allow you to hold less back. This still does not warrant using an unoptimized spec or gear set up, since with the optimized options you can relax a little bit and won't have to pour every bit of effort into pumping out damage. You could go get a drink and then come back and continue dps to give your tank a threat lead.
That last part was a joke. Please don't do that.
For the Horde and the Naaru!