Yay, Black Mage convention! Ok, Swiftblade is just absolutely perfect for this situation. With +4 effective sorc levels and I'm assuming a means of snagging prereq's relatively early, you could go :
Sorc 4/Spelldancer 2/Swiftblade 10/Abjurant Champion 4
This gives a means of persisting (and most of it's prereq's are also prereq's for everything else, other than Endurance), particularly your uberhaste, plenty of defense, a pile of offensive options (spam casting while still moving, or single cast while owning faces in melee), and party benefit to boot. Also, with a psionic tattoo of psyref, you can still pull the DK/SCM trick of XP-less spell revision, giving the same versatility. Sexy!