Once again, just like I pointed out in this Batman post, everything that was wrong about the first X-Men Christmas episode was corrected here.
On Angel's Wings aired during the second season of X-Men: Evolution in 2001. In this story, a new hero is seen in Manhattan rescuing people in trouble. His name is Angel and he is a mutant, but the public doesn't know it. But when the public does find out, and the very people he had saved quickly turn into his persecutors, it drives home Xavier's need not keep the identities of the X-Men a secret.
Having this episode reiterate the mission statement of the series instead of getting overly Christmasy was a good idea. It doesn't stand apart from the series as a special episode but it does deliver a heartfelt story. The animation is also on par if not better than most episodes. Nothing was rushed so that they could get this out on time and the result is vibrant colours and beautiful backdrops and really nice movements.
If you wish to see this episode, it is included in X-Men: Evolution, Season 2, Volume 2 - Powers Revealed.