I use Glyph of Howling blast and absolutely love it. Plague Strike has been removed from my rotation and I generally only Howling Blast to refresh the disease. If you're lucky you can keep up FF an entire fight on Rime procs. It also free's up a GCD to get a Frost Strike in. Having the FF immediately applied to an AoE group allows for double damage BB's straight off the bat.
EDIT: Just looked at your spec and Glyphs, immediately replace dark command and death and decay with Obliterate and Howling Blast.
I would not take Icy Talons and would put those points into KM as it's a huge increase in threat and damage. I don't like morbidity as a Frost Tank and think it's a waste of 3 points that can be used more efficiently elsewhere. Lichborne is also a terrible talent since the nerf. You can check out my DK and current specs under my WoW characters, name is Drakiir.