I think that DRK's elemental magic (Tier I-III) could be eliminated and replaced with a set of elemental spells similar to some found in other square-enix games, notably the "Dark -ga" spells like Dark Firaga, Dark Blizzaga, etc. In fact, you can look no further than a certain mission boss in FFXI that uses Dark Flare, Dark Freeze, Dark Tornado, etc. These spells are either conal or radial, are cast instantly (however, they are "TP moves," not spells,) and inflict debilitating status effects.

I think DRK should get a set of "Dark -ga" spells that cost a relatively low amount of MP (100-200), have very short casting times (1-2 seconds) and inflict 1-2 status effects related to its element (i.e. Amnesia with Dark Firaga.) It goes without saying that these spells should also be Area of Effect. To boost their damage, these spells could either a.) be affected by Souleater: Take 10% of the user's Max HP and add that total (or double) to the damage of the spell, or b.) do high damage and always require 10% of the user's Max HP as part of the casting cost.

I would only hope that these spells have unique animations.