The small power of scratching itches could be used on your opponent. That same amount of force, applied to the brain, could instantly kill a human and even most supers. However, if it's more of a mental power, as itches are, in fact, mental constructs, it could be used to project an aura of calm around yourself, making people enjoy your company, and encouraging people to like you. Furthermore, it would relieve stress in both others and yourself.