With 3.2 on the horizon, Blizzard is finally implementing something they mentioned in planning weeks ago: Making a talent in the Frost Tree which makes the abilities a Frost specced DK gets (including Death Strike) hit with both weapons if Dual Wielding.
For those not keeping up with MMO-Champion or the patch notes, the talent is:
Threat of Thassarian: New 3-point talent. When dual-wielding, your DeathAdditionally the talent is deep enough in the Frost tree that only those going Frost can get it (or at least you can't get enough talents in another tree that you can reach a major talent in another tree).
Strikes, Obliterates, Plague Strikes, Blood Strikes and Frost Strikes have a
30/60/100% chance to also deal damage with your off-hand weapon. Off-hand
strikes are roughly one half the effect of the original strike.
Now, as a tank, I'm not immediately viewing this as the best thing ever. First and foremost, it's not made with DW Tanking in mind, since it doesn't effect Rune Strike. Mechanically Rune Strike is next to impossible to make hit with both weapons. This is, obviously, because it is based on the next hit, so having the off-hand attack as well would be a bit unbalanced (especially with 1H weapons having a much faster swing speed than 2Hs, so they could theoretically get off more Rune Strikes). Having MH + ½ OH damage every swing, plus additionally the normal ½ OH damage would be crazy damage, thus completely imbalanced.
Instead, a possible fix to making Rune Strike valid while DWing, would be a modification to it's threat generation. Currently Rune Strike does 150% damage plus a variable number based on AP, with a 150% threat modifier. If Rune Strike was changed to do the damage it normally does, only with (this is a random number and not truly reflective of the number needed to balance out the loss of damage) 200% threat modifier, our TPS would remain where it was with a 2H, while our damage wouldn't skyrocket. Now, from there, let's look at the pros and cons of DW vs. using a 2H.
Higher TPS: Two Hander
Straight numbers here. A DW attack, even if it uses two slow weapons, will still do less damage than a two-hander. It's just the facts. Assuming Blizzard does not do something for Rune Strike, there's the loss of TPS there too. While it's true that white DPS while DWing comes out ahead of a 2H (again, pure numbers), Death Knights' reliance on using weapon-based Strikes makes 2H a stronger TPS tool.
Side note: Remember that other classes that can use 2H and DW don't rely as heavily on weapon-based attacks as DKs do. Warriors only valid "strike" build is Arms, which only takes it's damage from it's main hand. Shaman only have Storm Strike (Lava Lash only does OH damage), plus the damage from weapon enchants. Basically, no other class is like a DK, so comparing it to other classes that can DW and pointing out how them DWing is better is a moot point.
Higher Overall-Survivability: DWing
As of right now, the most efficient enchant to use for a DK is the Rune of the Stoneskin Gargoyle. Granting 25 Defense (non-diminishing) and a 2% health boost, this generally makes up for a DK not having access to a tanking specific weapon and a shield. While it's possible to take something other than SSG, you have to give up a lot in other areas because you're losing out on Defense.
Thus I constantly see people say that losing SSG makes you lose 25 defense, which amounts to 3% avoidance, not to mention that gear needs to be regemmed/re-enchanted for more Defense. These people are forgetting one very, very important thing about being a DW tank, and that is that you can... dual wield tanking weapons. Considering that Broken Promise is the best 1H tanking weapon currently available to a DK (will go over this later), and it gives 8.75 points (not rating) of Defense , if you were to DW two of them, you'd be sitting pretty at 17.5 Defense, thus meaning the loss of SSG actually only equates to a loss of 7.5 Defense points, and lose a grand total of 0.9% avoidance (and the 2% health bonus).
What I trade for those losses it the gain of 4% undiminishing Parry, along with a 50% reduction in disarm duration, and that's not counting any additional avoidance that one gets from Parry, Dodge, or Defense Rating on the two tanking weapons you choose to use. So in the end it's a decent gain in the avoidance department.
So! Great stuff, right? Well... not really. The catch on all this: Blizzard isn't changing how the damage is based. All the attacks that are modified by ToT still do a % of weapon damage, which means you still want the weapons with the broadest damage ranges that you can get. Basically, fast weapons are bad, slow weapons are good.
No problem, right? Well... not really. Go run over to Wowhead, go to the PTR side of things, do a quick search of one hand, main hand and off-hand weapons useable by DKs, are iLVL 200 or higher, and have defense rating on them, but are slower than 2.0 speed. Go on, I'll be here when you get back...
What did you find? Unless they added anything new since last night when I checked for new stuff all you found were the Infantry Assault Blade, a blue iLVL 200 sword from Heroic Utgarde Keep and Broken Promise, which drops from Heroic Naxxramas. That's it folks. Two weapons, and even the best clocks in at only iLVL 213.
So by the time you're poking around hard modes in Ulduar or even normal mode on new instance when it comes out either tomorrow or the week after you'll start trailing behind in terms of available stamina. I mean, the amount of stamina that two Broken Promises gives you is about equal to what any other 2H will give you. By the time you start picking up even 10-man ulduar drops you're trailing, and you just keep falling further and further behind. While additional avoidance is good, falling behind in terms of EH is actually worse IMO. I've always been of the opinion that as long as you aren't neglecting either, EH > Avoidance. And yes I know it's only a little difference... but it will add up, of that I have no doubt. "Only 500 health" turns into "only 1,000 health" and keeps going.
It just doesn't justify itself in the end using two BPs when you have a perfectly good, up-to-date 2H.
Now, it's not a complete no-go. We don't have the full drop table from the new 5-man and the new raids, so it's possible that we just haven't seen some new slow 1H tanking weapon, but with Blizzard's track record, I wouldn't go holding your breath. Consider... one slow 1H tanking weapon in all the heroics (and only a blue, not an epic), one slow 1H tanking weapon in all of Naxx (both 10-man and 25-man), and absolutely no slow 1H tanking weapons in Ulduar, despite having something like over 800 pieces of loot between the 10-man normal and heroics and 25-man normal and heroics. If Blizz does add a slow 1H tanking weapon in this patch or in Icecrown, I'll do a respec, but for now it looks like I'll continue to use a 2H.
Addendum: I'm really thinking about how I'm going to respec for my frost tanking build. One of the other changes in 3.2 was dropping Blood of the North from 5 points to 3. Previously I had just enough points get what I needed for a 15/51/5 build but now with my two floater points, I'm not sure where to put them... it'd be one thing to slip them over to Unholy to get something like increased disease duration, but they need to stay in the Frost tree so I can get Howling Blast.
I'm considering pulling more points out some of the handy but not necessary talents to go for Icy Talons and Improved Icy Talons again. I had it before, but dropped it because we almost always have my girlfriend who plays an enhancement shaman. But with these damned floaters I might as well go for it and have her throw out the spell haste totem. It'll decrease my TPS a bit, but should boost overall raid DPS and I think that's probably the best for the guild. I mean, it's not like anyone can touch my TPS except the hunters when they are being stupid and not FDing... *glares at hunters*