If you mean power level, I think she's perfectly fine as she is. Not all the X-Men need to have the most versatile or strongest powers. If I had to add something, I'd say that she could make simple firework constructs (i.e. imagery) for aesthetic purposes.
If you mean overall effectiveness, I feel she could fall along a similar role to Gambit as the sly rogue, but instead focusing on distraction and diversion. She could light up a compound in blinding fireworks and lead armed forces away from crucial positions.
