Traditional legends say that if a unicorn's horn is severed anywhere but the base, it will become a half-dead, zombie-like unicorn. As the magic spills out of the horn, all the life, color, magic, and freedom leaves its body, leaving it lifeless, gray, realistic and strict.
Art (c) Christina Jacob
Link
Luminaria
Interesting. I never knew that, but your picture does a great job portraying the legend