I never thought about that kind of idea before (never played BLU ... or even unlocked it :/ ) but what you're saying would be an awesome idea. And maybe not only give you special attributes, but what if combining certain abilities in the same action slot gave you a unique ability ... like (going on just the Armory system now) combining Provoke and Taunt to make a stronger Provoke, or combing a weapon skill like Howling Vortex with a magic spell augments that weapon skill with the type of the spell such as Fire, or if it already has a Fire augmentation then it makes it stronger. Just some ideas, not fully thought out of course ^.^