After slaughtering 50,000 damage worth of lvl 22-24 Ogres (being approx. 75 Ogres @ 650hp each) in Duskwood's Vul'Gol Ogre Mound, my level 20 Arms Warrior armed with the 2H Reef Axe from Blackfathom Deeps averaged 82.5dps, as seen in the below screenshot. (Yes, I cut & pasted the Recount Window into a second screenshot.)
After repeating the experiment and terrorizing the Ogres a second time, this time as a Fury Warrior but still with the exact same gear, I averaged 94.6dps. As you can see from the second screenshot the passive buff from the Fury Tree's "Precision" skill, being +3% to Hit and +40% to Autoattack, provides a significant boost to my base/white Damage, and definitely helps to explain the almost 15% increase in overall DPS.
I ran Shadowfang Keep as an Arms Warrior in between the two attacks on the Vul'Gol Ogres, and with all of the group buffs and the passive buff from using the Random LFG Tool I managed to pull 100dps, being the same as what I managed on my own as a Fury Warrior.
After respec'ing Fury, traditionally a dual-wield Build, I first equipped two Baron's Scepters and slaughtered a dozen or so Ogres, just to see how well Fury worked when dual-wielding. In short, it didn't. Using what are probably the best two 1H weapons a level 20 Fury Warrior can get my DPS averaged in the mid-70s. It did jump into the low 80s when I got in a string of Crits, but would just as quickly slide back into the mid-70 range when my Gnome went nose-to-kneecap with the Ogres for longer than a few seconds, which as a dual-wielding Fury Warrior it usually did.
In fact fighting the Ogres as a dual-wielding Fury Warrior felt almost exactly like fighting them as an Arms Warrior, with combat usually lasting at least 5-6 seconds. I noticed I missed many attacks, and also got Parried a lot. Even with the combined +4 to Hit buff from wielding two Baron's Scepters, the lower damage output meant I was still in combat for a lot longer than when I equipped the Reef Axe (as Fury). The bonus to Hit from not dual-wielding meant a lot less of my attacks got Parried, and thus a lot more of my attacks landed, and when you're hitting Mobs with the Reef Axe they know they've been HIT!!! As a Fury Warrior wielding the Reef Axe it was not uncommon to rush into combat and lay out an Ogre within 2-3 hits, and with the first three attacks being Victory Rush, Autoattack, and Bloodthirst, those 3 attacks could all land within 2-3 seconds. If even one of them was a Crit it was usually lights out, but if the Ogre was still standing and Execute hadn't lit up I'd throw in a Heroic Strike and that would inevitably get the job done.
The end result from terrorizing the Vul'Gul Ogres is what I've argued all along, that at lower levels Arms is a sub-par DPS build to Fury, and that even if you have two of the best one-handed weapons available for your level you're still better off using a comparable 2H weapon instead of dual-wielding. In my case, 15% better off.