Resto and Earth Shock?Follow

All tanking classes have abilities/talents that (should) include a superior (20%) melee attack speed debuff. You are not expected to keep it up under normal circumstances.

Just to add (not correcting you, I'm just bored and more information doesn't hurt):

DK tanks normally have a 14% one, but it is increased to 20% via a 3 rank talent in the first tier of the Frost tree. All DKs should always keep up FF, so this is fairly reliable (and it's great for trash, as it is a 20% debuff for all the mobs you are fighting).

Paladins don't normally have one, but there is a talent in the Protection tree, Judgements of the Just, that gives a 10% debuff per point (2 points). It also gives them 2 other nice buffs (not awesome, but nice). To apply, you need to place a judgement on the target (generally Wisdom or Light) which will last 20 seconds. As long as the judgement holds, the debuff will too. So, it it easily applied and kept active on single targets, but not easily applied to extra mobs.

Warriors have Thunder Clap. It normally only provides a 1o% debuff, but a 3 point talent in the first tier brings it to 20%. It lasts 30 seconds and TC has a 6 second CD. Luckily, the talent also boosts its damage by 30% and it's rage cost by 20%, so Warriors want the talent even without the debuff increase. Like DKs, it can be applied easily to all mobs.

Bears kinda get the short end of the stick here. They get the 20% debuff from a 3 point talent, which will let 3 of their main abilities apply it. However, there isn't really a useful secondary effect like with the other talents--they will take the talent just to apply the AS debuff. They can easily apply it in an AoE scenario though, due to swipe causing it, but less easily than with Warriors/DKs. However, they will keep it up with less effort than Warriors, due to their high threat skills causing it, when Thunderclap isn't exactly the best skill in the world for single-targets.

All of these are superior to ES, in that they reduce twice as much and have a much longer duration (and are more easily applied in a normal rotation). ES has a very small window before it drops. You should never be in a situation where you need to provide it.

One note, however, if you are every doing something with an Arcane Mage and there isn't a dedicated tank (like if you are running with 4 DpS because you can keep everyone up w/ Chain Heal if the clothies aren't getting hit or you're doing PvP), he will love you if you keep the debuff up, as it will increase his DpS by 12%.

Of course, in the case of PvP, your EB Totem will do the same job.

Well then, DKs and Warriors still have a much easier time in AoE (and DKs have the easiest time overall, I suppose).