Well I would think of Blood magic almost Like Affliction With What He said like health drain or affliction damage with alot of damage over time or bleeding effects stuff like that probably nether the less i cant wait

ya i agree with moonpaladin. blood will most likely have bleed effects,probably dots and draining spells

unholy is probably the shadow/ spell casting side of the deathknight and blood is probably melee with bleeding effects and stuff like that.

i think blood majic will be purley melee dps and dots