Seal of Blood is mostly for instances, even though it can do more DPS then seal of command, its true purpose (in my opinion) is to keep your Mana comming in from heals(not your own heals mind you). letting you go all out, for longer periods of time.
that said, i dont think it would be very effective/efficient to use SoB in solo. the increase in DPS you may get would not off set the mana healing your self back up.
again, that is opinion, as i have not actually tested this.
also, if your are going primarily ret, then you should have a lack of spell damage. making judgement of SoC not really mana effective. judge only when your seal is about to wear off, or right before you kill a mob so you have a fresh seal for the next or something of that nature.
as for aura, you should be using Sanctity. Ret spec is a 1vs1 spec, and Ret aura is terrible for that.
Edited, Jan 31st 2008 3:05pm by RuenBahamut