This being said as it has been pointed out; a death knight is a strong DPS sort of tank. We don't rely on "causes a high amount of threat" abilities to build aggro, instead, we rely on DPS'ing smart and holding up our tanking abilities at the same time. Right now as it stands, since we don't have the ability to equip a shield that does get rid of quite a bit of mitigation through both armor and shield block. This is easily made up in avoidance, but without the general standards on a shield getting a higher health pool will be harder, but not by much. One of the great things is when it's a controlled fight with predictable cooldown on mobs/boss abilities we can easily negate much of the damage through our various abilities (i.e. Icebound Fortitude, Lichborne and the like(.

Abbreviations Used:
Avoidance: Dodge\Parry\Miss
DPS: Damage Per Second or Damage Dealing Class
Mitigation: Damage reduction (i.e. spell damage reduction and armor)
GCD: Global Cooldown
DoT: Damage Over Time
AoE: Area of Effect
HoT: Heal Over Time
RP: Runic Power
IT: Icy Touch
PS: Plague Strike
HS: Heart Strike
SS: Scourge Strike
BB: Blood Boil
HB: Howling Blast
HC: Hungering Cold
Ob: Obliterate
UB: Unholy Blite
DnD: Death and Decay