Procs make everything cooler
So you've probably heard the rumors that unholy DPS is actually incredibly strong in Patch 4.3 -- strong enough to be worth taking. It's all thanks to one thing: Gurthalak. Some DPSers have shied away from this weapon because it features no secondary stats, but I just want to confirm something: You are wrong to do so. The proc on this sword more than makes up for the lack of secondary stats. This for one simple reason: It summons a tentacle that does massive amounts of shadow damage. This shadow damage is affected by Dreadblade, the unholy mastery. This fact is so potent that it pushes mastery up past critical strike rating for unholy death knights with this sword (haste, of course, is still king).
So the question becomes how strong is too strong? Is Gurthalak overpowered? Some say yes, but others point out (and I tend to sympathize with this) that it is, at the moment, about the only thing making unholy truly competitive with dual wield frost at the endgame. Blizzard could solve this by making the Gurthalak proc non-stackable with mastery, in theory, but would that solve anything except making all serious raid DPSing death knights return to dual wield frost DPS? That's unclear.
There are two discussions to be had here, I think. The first is to ask if a spec should have to depend on one specific item to be competitive. Certainly, it's a given that some classes are dependent on gear to be good more than others, but one item might be pushing it. However, if it's one item, the fact remains that it is allowing the spec to be competitive. It is allowing people to choose to spec into something they like to play without being an undue burden on their raid group. In that case, it seems like the ends certainly justify the means.
The second is the idea that maybe the ultimate reward for the expansion deserves to be a little overpowered. For a melee DPS, their defining piece of equipment is probably their weapon. When you think of iconic weapons, you should think of endgame equipment. In the past, we've had iconic possibilities such as the Bryntroll or the original Ash'kandi. This time, Gurthalak and Souldrinker are both worthy successors, if not in look then in the unique procs they bring which give you a sense of power that a character who has risen so high as to defeat Deathwing himself should have.
So is Gurthalak overpowered? Possibly, although I will note it isn't doing two-handed frost any favors at the moment. Does it need to be? I say yes. Certainly, Blizzard should focus on making unholy and two-handed frost competitive on their own merits again in patch 5.0, but until then, if Gurthalak is providing some relief and some choice in our endgame DPS specs, I say it's a good thing. It's better than having everyone feel pressured to spec dual wield frost.
When one thinks of powerful trinkets, there are three major entries to consider. The first is the Bone Link Fetish, which includes a powerful Whirlwind-style attack that does appear to stack with attack power. The second is the Eye of Unmaking, which provides a massive strength boost as long as you're in melee combat, and the third is the Creche of the Final Dragon, a more traditional strength trinket with a critical strike proc.
The Eye of Unmaking is easily the most powerful DPS death knight trinket available this tier. Depending on the item level, it can add 780 to 980 mostly static strength to those long boss battles. Sure, there's always the danger that the buff will drop, but on most fights, you should be in melee range often enough to keep it going. Strength remains far and away the best death knight DPS stat, so it's more or less a given that this wins out in most situations.
Creche of the Final Dragon occupies a more awkward situation. Critical strike rating has long been the redheaded stepchild of death knight DPS stats, although recent bug fixes have given it a new life. That said, it's still not the greatest. Parsing and math so far suggest it's still second best for frost death knights though. Bone Link Fetish is the fun melee trinket of this tier and appears to be the second best trinket for unholy death knights.
The final tier of an expansion is a great place to bring out the unique gear for sure. In ICC, it was Bryntroll and Deathbringer's Will. Good art for a dungeon tier shouldn't be underestimated for sure, and iconic item sets will always have a place in our hearts. But anyone can look amazing.
What really sets us apart and takes our characters to the next level is acting amazing. Last expansion, we got to take on the form of ancient powerful races and steal the health of our enemies. This expansion, we get to unleash a whirling maelstrom of destruction and summon eldritch horrors from the deepest earth to lay waste to our enemies.
To me, arguments about being overpowered are secondary. The point is that we look and feel amazing in battle. That is something that gives us agency in our characters and makes us feel set apart. That is definitely worth fighting for.
Learn the ropes of endgame play with WoW Insider's DK 101 guide. Make yourself invaluable to your raid group with Mind Freeze and other interrupts, gear up with pre-heroic DPS gear or pre-heroic tank gear, and plot your path to tier 11/valor point DPS gear.