Darkness wielders are unknowingly wielding light. If you keep in mind that you could make a room dark by removing light, and that there is a spectrum of invisible light lengths, one amusing explanation of darkness powers is that "darkness" wielders just aren't aware of what they actually wielding - plus its an awesome plot moment when someone suddenly doubles the nature of their powers at a late point in the story.
Darkness users are actually manipulating space, photons go bye-bye. The physics thingy which carries light is known as a photon. Sometimes it behaves like a particle, sometimes it behaves like a wave. If you willing to say that when your "Darkness" wielders use their power the photons disappear in the affected area, then the abilities you describe could be explained by directly manipulating space.
Anti-light! When matter and anti-matter collide they completely annihilate each other, releasing an explosion of energy and photons. Photons can't be annihilated because they have zero charge (matter has positive charge, anti-matter negative charge) which means that "light" has no true opposite. If you pretend there is another property of particles, and that photons are positive in it, then you could invent a negative photon, meaning there would be a type of dark light which would annihilate photons (and light) on contact in addition to the darkness which is just the absence of light.
3)Anti-light! When matter and anti-matter collide they completely annihilate each other, releasing an explosion of energy and photons. Photons can't be annihilated because they have zero charge (matter has positive charge, anti-matter negative charge) which means that "light" has no true opposite. If you pretend there is another property of particles, and that photons are positive in it, then you could invent a negative photon, meaning there would be a type of dark light which would annihilate photons (and light) on contact in addition to the darkness which is just the absence of light.
