Why not the pitchfork effect? Or the Bifurcated Tail Effect? Or the Brimstone Effect? I can think of a dozen better names for “things that are obverse to halos” than ‘Devil’. And this is to say nothing of the more likely celestial —in the non-theological sense— origin of the term referring to the bands of colored light surrounding a light source, caused by refraction, making the light source appear larger. Oy.