Gems: Change +Parry (In your Bolstered Legplates) to + Strength for better threat or +dodge.
Gear: Enchant what isn't, if that's an available option. (I myself haven't unlocked the Sons of Hodir faction, so shoulders don't bug me, but cloak (Titanweave or the agility enchant!!) and gloves (Armsman enchant) are an absolute must.)
Talents: With your expertise nonexistent, you're gonna get parry-wasted dual-wielding. Thus, take the three points from Threat of Thassarian, and the three from Nerves of Cold Steel, and move those into Morbidity (3/3 Unholy) and finish off Scent of Blood, as well as two handed weapon specialization. Also, if you could find a way to pick up Deathchill, it's a MASSIVE threat front-loader. Mobs hate being critted from the jump.
Rotation: Tanking as Frost myself, I prefer a single-disease rotation. This lowers the damage on Obliterate, and thus the threat as well, but makes things almost easy enough to manage aggro for my 9 year old son to tank Naxx 10. As you're running a double disease rotation, everything looks to be in order. I'd upgrade to the Sigil of Avoidance, which causes Rune Strike (HUGE THREAT BOOST) to give you an additional 136 dodge rating, and thus bigger threat via more rune strikes. Spam rune strike, and use your defensive cooldowns (UBA going in, IBF as soon as it's available) and judging by your rotation, you should do ok.
...Thoughts of a philosophical Death Knight...
If death is the inevitable end of life, is life the inevitable end of undeath?