What you don't have: My extra-special tips 'n' tricks for DK tanking (alas, I cannot find a way to make that "n" backwards). Let's rectify that.
I've been offtanking Ulduar as Frost, with this build and glyphs. High threat, high damage mitigation, and high chance of milk shakes for every 100th customer!
- In general, Howling Blast followed by Blood Boil can be very strong snap aoe threat. The glyph of HB is great for this, because it puts a disease up on every target, buffing the Bloodboils. In aoe situations, I tend to not bother with Icy Touch, Plague Strike or Pestilence, instead using those runes for an extra HB/Oblit and Blood Boil (or a Death and Decay). I call this "the IcyHot".
- Use the shortest cooldowns early. All else being equal, you should use Anti-Magic Shell first, then Icebound Fortitude, then Unbreakable Armor, then your trinkets one at a time. you can probably weave another AMS in there too, with it's 45-second cooldown.
- When tanking a single target (such as a boss), be careful not to be overzealous with your Frost Strikes (or Death Coils if you aren't Frost). It's more important to alway save RP for a Rune Strike than it is to keep your RP near zero.
- Get a mod that shows you clearly when you get a Killing Machine proc. Go out of your way to use a Frost Strike with the proc. If you are aoe tanking, use Howling Blast instead, but frankly you should be using Howling Blast every cooldown anyway if you are aoe tanking.
- You can do pretty decent dps while offtanking. As long as you have some aoe threat, there's no reason you have to always be attacking the things that are hitting you. When Razorscale is chained down, I just let the adds beat on me and help the DPS on the boss. When tanking Pummelers on XT-002, I just use HB and DnD every cooldown, but otherwise I spend the entire fight DPSing XT or his Heart while letting the Pummelers beat ineffectually on my armored ass. Just make sure you keep the adds in front of you to you can dodge/parry.
- Save aoe for the right moments. This is especially important if tanking the arena during Thorim (they invented the word "frantic just so I could use it to describe tanking the Thorim arena. True Story, Webster told me). The first few attempts, I dropped DnD at the start, and it went to waste by hitting only one or two mobs. Instead, watch your rune use and drop DnD when the large group of weak Citizens spawns. On that fight, I tend to save Death Grip for the Runecasters, DnD for the citizens, and Taunt for the Vykrul warriors. Then I just group everything up and spam the IcyHot while dumping RP on the primary kill target.
- You can damn near solo the adds on Ignis, especially now that the encounter has been nerfed into the ground. When they first spawn, taunt them off the healers and hit them with IT, then smack them with an Oblit or FS as soon as they get in range to solidify aggro. Then, turn and run directly through the fire patch. Watch the add and snare them with Chains of Ice when they are just inside the fire. Then, you can run around the outside of the fire in a circle, casting CoI every few seconds, to keep them in there. Now that it only takes 10 stacks rather than 20 to make them molten, this is extremely easy. When they have 9 stacks, run into the edge of the water (we have the tank move Ignis in a rectangle around the center line so the fire is always near a pool) and Death Grip, then call for a ranged dps to blow up the add while you run to grab the next one. Repeat.
- Use your ghoul to help the DPS. I tend to pop mine every cooldown on most fights, or specificially when Razorscale is chained down. Try to summon it right after a big aoe, rather than right before.
- Remember to stay in Frost Presence when tanking. I totally didn't wipe my raid on trash 3 times the other night because I was in Blood Presence. Totally. Didn't.
- When you need to switch to dps mid-fight, remember that you can switch presences, weapons, and sigils during combat. I have the luxury of having two separate weapons of similar power, so I enchant one with Stoneskin Gargoyle for tanking and one with Fallen Crusader for dps. If I need to switch to pure dps mid-fight, I equip the dps weapon, and Awareness sigil and switch to Blood Presence. Fights where this is useful include Freya and Iron Council.
- In an emergency when all of your other cooldowns are down, you can use Army of the Dead to mitigate a big hit. The secondary effect of channeling the spell is that your avoidance (dodge/parry) gets converted directly into damage reduction. If a Fusion Punch is incoming and all your defenses are spent, you can pop AotD and mitigate 40-60% of the impact.
Have a good weekend, I know I will.