The World of Warcraft Death Knight Blood spec is centered aroun physical damage abiltys.

The survivabilty in the Blood tree is the most effective tree for PVP with such talents as Mark of Bloodand also Rune Tap and Improved Rune Tap.

The World of Warcraft Death Knight Blood contains a high out put of physical damge is very powerfull in the Arena setting, with such talents as Heart Strike combined with the Glyph of Heart Strike is deadly.

The World of Warcraft Death Knight Blood spec for PVE is in my opinion the best suited for tank it has its own unique survivability traits.

For example Vendeta it will heal you up to a certain amount of health when you kill something that grants you honor or experience.

Also one of the best tanking traits is Veteran of the Third War which grants you extra strength and stamina which both of these are essential to tanking.

With abominations Might it will increase you attack power as well as those in your party or raid.

Blood Gorged is very help full because it will deal more damage when you are above 75% health and also ignore you targets armour for x amount.