Sephiroth is perfectly named as the one winged angel. One winged angel means fallen angel. Well, Sephiroth was not a bad guy. In fact, he was a role model to young people. He was loved, admired and respected. Sephiroth was also a treasured General of Shinra. He did win the war against Wutai. (at least that's what I heard). The time and place that Sephiroth lost his "wings" and fell to the depths of evil was when he found out about the Jenova Project. Knowing that his mother was experimented on drove him insane. In a way, Shinra, who was doing the experiments, was the one who cut his wings (hurt him mentally and emotionally). Ironically, it was Shinra who needed him the most, because he was their strongest fighter.