Could be a Japanese version replacement for the English name, considering that the Japanese like to stylize names and such, like Lightning's special attack being called "Scene Drive," but replaced with "Army of One" in English, and a few others I can't remember right now because I'm tired >_< Usually putting Drive, Buster, Break, or something similar
"Killing Face" is still odd though, haha. Maybe it's because his face so so ugly, you just feel the urge to kill it. Or looking at his face kills you. Flashbacks of the SIGIL OF PAIN in D&D games, haha.