Open your character details, hold shift and left click. You'll notice that the "attacks per second" will change depending on which weapon is to be used next.
With that in mind, basically what happens is that each swing will have a different time.
Now, lets say you equip a dagger in OH, you'll have 1.25 attacks per second lets say with the MH as next weapon, not the dagger. Now, remove that dagger and put in a dagger with IAS. You'll have 1.35 or something like that.
The build is based on critical hits or fury from a Mighty Weapon + Weapons Master. The more hits, the higher the chances of criticals, the higher the number of critical hits the higher the chances of having Fury back from Battle Rage, or in the case of the Mighty Weapon variation, the more hits, the more Fury.
Also, the more hits, the more health back due to Life on Hit. If it was Life Steal this would be irrelevant, just the damage would matter, but we all know that Life Steal is baaaaaaad now.
Your example also doesn't make much sense:
A 1h 1200 is better than a 1h 11??. Period. However, if you meant a 1h + IAS = 11?? versus a 1h (no IAS) = 1200, then there would be some discussion. Still, I think I would prefer the +IAS version since it would also affect the OH speed. You would hit more often thus increasing the effectiveness of your build.Quote from keik
I ask this as I am currently trying to decide between higher DPS i.e. 1200 1h maces with 8+ % IAS, or 11xx 1h maces with 0% IAS (Yes, both contain sockets). Right now I seem to be unable to find a spreadsheet designed specifically to simulate WWSprint barb action. (Any help on this front would be particularly helpful too!)
Anyway, my personal preference is the faster the better for LoH and Fury generation. I use that build with Axe + Dagger, or Mighty Weapon + Dagger.