Remember that your character sheet represents how you interact with the story, not how your character 'actually is' so you also have to consider how effective you want your 'failures' to be. For example, if want to place a maneuver on someone using evocation, I could narrate the effect of a successful evocation maneuver as me failing the evocation, and the actual aspect placed on the other guy could be 'laughing too hard to pay attention'. But mechanically, I did and evocation and placed and aspect.
Option 1:
Just have it as a character aspect, and invoke it for effect/compel if for the failures.
Option 2:
Get a one point power that lets you attempt maneuvers using a magical related skill (i.e. discipline, conviction, or lore), selected at the time the power is defined and call it 'minor magic'.
Option 3:
Take the full selection of magical power, and compel it all the time.