Yes, by "best" I am referring to a person (I think). The phrase refers to the fall of Satan. As you know, Satan was a fallen angel. But he wasn't just an angel. He was actually a seraph, one of the seraphim. According to Christian belief, there are nine choirs, or levels, of angels. "Angels" followed by "archangels" are at the lowest levels, whereas the highest levels consist of the "cherubim" and the "seraphim." The seraphim were the highest choir of angels, the most powerful of all angels and most closest to God. As the story goes, Satan the seraph, one of the "best" of all angels, rebelled against God, was corrupted and ultimately became the worst thing ever imaginable. I've heard that this Latin phrase - "Corruptio optimi quae est pessima" - comes from the Middle Ages and refers to the fall of Satan.
I'm thinking about getting this Latin inscription done as a tattoo, but I want to make sure it's correct, of course. Is the correct Latin translation "Corruptio optimi est pessima"?