Going off of silent's bit, it'd be interesting to make BLU a Garlean/Ascian class. Have them using the same Eikon-draining power as Ultima used, on a smaller scale, and have them gain abilities off of the various Primals. Landslide from Titan, Radiant Plume from Ifrit, Wicked Wheel from Garuda, etc. Use a Gauntlet and Gun-hybrid weapon for their arms