SPOILERS Noah screwed Xande over!
It's obvious that the three apprentices are not immortal, as throughout the game you kill Doga and Unne, and later they die for real by joining "the great soul" or whatever. So when Noah gave Xande mortality (which is a pretty lame gift anyway) wasn't he giving him something that he already had?
OH! And for that matter, who would want to live in a world where time was completely frozen? Wouldn't that mean Xande was just walking around the purpley world with nobody to talk to and nothing to do? That's definately a fate worse than death in my book.
Noah's an ass!