As I mentioned last time, it's time for a rant about DK tank weapons. When DK's were created, we shook things up just a bit. Long story short, we tank with two-handed maces, swords and axes mostly, and the trouble was, they don't make tanking two-handers. So, instead of retrofitting a ton of old content to accomodate Death Knights, they decided to simply keep rolling out DPS two-handers and give us Rune of the Stoneskin Gargoyle. This works out well enough, but you still need something to put the rune on, and some things are better than others.
So what should be the vessel for your runeforge? Let's look at the stats 2h weapons can have.
Strength - Helps your DPS, and thus your threat. Grants parry rating via Forceful Deflection, scales well with certain DK talents.
Stamina - Every weapon has this. However, the more, the merrier. Also scales to DK talents and Frost Presence.
Agility - Although not specifically boosted by our class, this gants a sizeable chunk of Dodge and some Armor, as well as Crit for threat. Better than Strength for mitigation/avoidance, usually worse for threat.
Intellect/Spirit/MP5 - No. Go unarmed before you use one of these, it'll be funnier and about as effective.
Expertise - A nice boost to threat and a small drop in incoming damage due to less parryhaste. Try to get around 6.5% total, but it's ok to go past that. About twice as effective in the hands of a tank than it would be used by an intelligent DPS.
Hit - It sucks when your aggro moves miss. Get to 9% total (remember to include talents) ASAP, but there's not much reason to go past that. A dead stat if you're already capped.
Crit - A percent mod to threat... if your moves can crit. Not as useful in my Unholy spec.
Armor Penetration - Solid for a Blood tank, rather worthless for other specs, which deal primarily magic damage.
Haste - Useful, but go for something else. It only reduces the GCD on your non-weapon attacks, and speeds up your melee swing. It does not, however, increase the rate your runes come back, so even if you use mostly spell attacks, it will just increase your downtime. Generally worse than crit.
Attack Power - Ups all your threat. No mitigation bonus.
Resilience - No. Not unless you're just gearing up and not yet Defense capped, and even then, this will be worthless post-3.2.
Now, there's a slight problem. You may understand, and I may understand that a Strength/Stamina/Agility/Expertise item is exceptional for tanking, but there are legions of DPS out there that can also use your loot. And it will be a valid upgrade for them too. They want it. They'll get it, toss aside their old blue junk, and then replace it a week later. If you are leading a raid, or have any say at all, make it perfectly clear that Joe Roflstomp getting the Inevitable Defeat over the local tank DK is like Mr. Rogue Lolstab getting the Skyforge Crossbow over your Hunter. Yes, they can use it, but is everyone really stupid enough to put it to such a waste? Unfortunately.
Here are some recommended tanking items found between just dinging 80 and just breaking into Ulduar.
Crafted(Blacksmithing) - Titansteel Destroyer, because it is really easy to get.
Heroic DTK - Mojo Masked Crusher
Heroic HoL - Colossal Skull-Clad Cleaver
Heroic Naxxramas - The Jawbone
Heroic Naxxramas - Inevitable Defeat
Heroic Ulduar - Worldcarver
Obviously there are others you can use, but these are some of the ones that I feel really should be used by a DK tank.