My first white LEDs where the Photon wide angles. Remember those? The cool white color reminded me of the brilliant blueish white light of an arc welder. A light so bright that you couldn't stare at it for very long.
I didn't want to call the light, "the welder", so Arc was picked. /ubbthreads/images/graemlins/smile.gif
If you want, it could stand for "A Really Cool" light.
Peter