I'm not making a huge theorycrafting thread here or trying to really analyze the entire tree, but I would like to know how this is useful.

http://www.corsec.org/images/devastate.jpg

What you see there is a description of the Devastate talent in 2.1. It states, "An instant weapon attack with both weapons that causes 50% of weapon damage plus 15 for each application of Sunder Armor on the target."

Now, I played around on the test server a bit, and Devastate was hitting for the same as it does on live when you have a Sword / Shield out. I didn't get to do any real testing yet with two weapons...but I'm curious why our 41 point talent for Protection just keeps leaning more and more towards dual wield. It seems they want to give us a talent for farming rather than any sort of passive threat scaling upgrade.

You get 2 attacks while dual wielding, much like Mutilate. Right now the offhand damage modifier is only applied to the weapon damage. You still get the full 175 damage for 5x SA, even with your offhand. With Mallet of the Tides and Blazeguard, I was hitting around 300+200 in full tanking gear.
Devastate is a decent replacement for SA while tanking once you reach 5 stacks. A bit more threat than unimproved SA, a bit more raid damage.
The second purpose is protection warrior DPS. Sometimes you just can't get around it because of encounter design. With the recent change, it will be even better than before.

But the main question still remains (and I guess I should have worded this better), how does this benefit someone who spends 95% of their time with a sword / shield combo?

It doesn't. This devastate change was to make non-tanking prot warriors not completely useless.

It certainly ups the DPS of prot warriors that aren't tanking (something feral druids have a huge advantage in atm--that is, being useful if they're not tanking) and perhaps gives people that aren't tanking an easier time trying to stay up on the agro list given that they aren't getting all the rage from being hit.

The change doesn't affect someone who always tanks, except for those few encounters where everyone DPS'es, like Aran. But it is very good for offtank DPS and probably for staying second in aggro, if that is ever required.

Edit: beaten to it^

There's some math on page 2 this thread: Max DPS for prot warrior?

Is it a bug or the adicional threat from devastate was removed ? At least on the SS that opens the thread it isnt present.

Edit: "The change to Devastate in 2.1 is being reverted and will not be a change for the patch once it goes live. We've done some additional damage testing and the output is in far excess of what we had thought it would provide"

http://forums.worldofwarcraft.com/th...sid=1&pageNo=8

Without doing any extensive testing, it did indeed seem pretty high because of the full SA bonus for offhand.

and of course, int the grand world of blizzard, "this ability needs a buff" + "oops we buffed it too much the first attempt" = "lets not buff it at all".

i hope when blizzard class devs wake up every morning and get in the shower, they only have the choice of ice cold and scalding hot water. no middle ground for us, no middle ground for them.

There’s some indication that Devastate is now in a state where the off-hand gets no bonus from Sunder Armor, but both hands still get an attack. (I have not yet been able to get on the test server to corroborate this.) Presumably, this would be a tweak from the devs to see if the dual-strike Devastate is workable at all.