I have yet to be guilded with more than two other warriors at any point in time since Cataclysm launched. I've had more rogues and warlocks than warrior guildmates, and those are the two least-represented classes in World of Warcraft. While I can't prove it, I suspect a lot of the warriors out there are alts, not often played these days. What I do know is, especially in a 25-man raiding situation, I have not been seeing a ton of warriors.
However, one thing is indisputable: Arms is the most-played spec of the class. There are more arms warriors than protection and fury combined in heroic Dragon Soul. Arms is, by far, the most popular spec the class has to offer right now in both PvE and PvP.
It was not always so. For most of Wrath of the Lich King and Cataclysm, arms lagged well behind fury both in terms of the damage it could do and the popularity of the spec, although its prominence in PvP kept it afloat. The reduction in the Mortal Strike debuff as Cataclysm launched hurt arms in PvP, but the nerfs to Vengeance and fury's mastery meant that all warrior specs suffered. Arms is just one of the pack there, while repeated nerfs to fury and small adjustments to arms gave it the eventual dominance it now enjoys.
Make no mistake: Outside of a few exceptions who just showed more natural skill with the arms priority proc system than fury, arms simply couldn't compete as a PvE DPS spec before patch 4.3. I personally raided as DPS throughout heroic T11 and through normal to heroic T12, and I always did more DPS as fury. As soon as patch 4.3 dropped, I was able to reforge my gear and do significantly better DPS as arms. Say what you like about skill -- I didn't suddenly improve as an arms warrior or suddenly forget how to play fury.
If you remember the end of Wrath raiding, arms was one of the four worst-performing specs in ICC. That was fairly accurate for the spec throughout all of Wrath, and despite improvements like Colossus Smash's replacing Execute in the regular rotation (thanks to Sudden Death) and Rend being refreshed by Mortal Strike so that it only required one application, arms remained an underperforming DPS spec.
Arms saw repeated adjustments in 4.1 (Strikes of Opportunity saw a 10% buff), then some nerfs in 4.2 (Recklessness and Deadly Calm could no longer be used at the same time, Two-Handed Weapon Specialization was nerfed from 20% to 12%). Alongside Overpower's getting a 1.5-second cooldown and Recklessness, Retaliation and Shield Wall's losing their stance requirements meaning that arms no longer had to stance dance to use one of its only real pure burst cooldowns.
Despite all this, it wasn't really anything that happened to arms that caused it to rocket to supremacy among warrior specs in patch 4.3. No, no amount of tinkering with our mastery, nerfing or buffing abilities like Two-Handed Weapon Specialization or Overpower did the trick. It wasn't even cool synergy with the protection ability Blood and Thunder that allowed arms warriors to spread Rend that really helped arms ascend to the top of warrior DPS. It certainly wasn't buffing Mortal Strike's debuff back up to 25% -- that barely had much affect on PvE and none on PvP, where warriors simply lack any meaningful pressure.
No, it was the nerfing of fury to depths that really exposed how powerful arms' ability to ignore periods of low rage really is. As long as fury did enough damage with its specials, and its Deep Wounds damage benefited from Precision as well, fury was capable of ignoring how impossible it was to get enough hit to generate smooth rage. Once fury's damage output was nerfed and the Deep Wounds bug was fixed, fury plummeted to the bottom of all DPS specs in Cataclysm, where it has remained ever since.
In short, arms warriors can control their rage to the point that they can freely spend it, and arms has the biggest variety of ways to spend that rage to inflict damage. The only thing arms lacks is a true DPS cooldown, which is what I argued was holding the spec back in patch 4.2.
Best in class
What's funny here is that arms is one of the best melee DPS specs in the game right now, not because it was buffed in any significant way but purely because its rotation was simplified enough (allowing Mortal Strike to refresh Rend was a master stroke) and the buff to melee attack power abilities like Blessing of Might benefits warriors more than other classes. Classes that were mechanically buffed, given legendaries, and otherwise handed all sorts of advantages are still complaining about arms warriors who weren't in any way given anything in 4.3.
It's just that the spec benefited from fairly low stat caps, a solid mastery for its second stat after critical strike rating, and the ability to control and use rage far more effectively than fury. It doesn't hurt that certain fights either completely trivialize rage (Ultraxion) or give you so many targets, making abilities like Blood and Thunder and Bladestorm really shine (Yor'sajh, tomb phase on Hagara, Blackhorn, Madness, even Spine if your healers don't mind).
The easiest solution would be to remove the ability to disarm warriors using Bladestorm, a change that reduced the only real threat warriors provided in PvP to a meaningless joke. I don't expect to see this, so arms will remain as underrepresented in PvP as it is now. I personally still like PvPing as arms for being able to Throwdown, but when I can be disarmed right after I finally manage to pin down yet another slippery ranged with 10 different ways to kite and avoid damage, it's very frustrating.
As it stands right now, arms is not just king of warrior DPS -- arms is king, period. Next week, the dethroned, deposed, scrappy underdog that is fury. How the mighty have fallen.
At the center of the fury of battle stand the warriors: protection, arms and fury. Check out more strategies and tips especially for warriors, from hot issues for today's warriors to Cataclysm 101 for DPS warriors and our guide to reputation gear for warriors.