Ah, but that sorcerer is indeed very ancient in lineage and, moreover, while his years might not be more than, say thirty, he's suffered the length of his lifetime. That is bound to leave its mark on a man, and age him beyond his years. I always thought that Janus looked morose and sullen, the epitome of melencholy; the appearance of being aged comes from this.
Personally, though, I've never much liked that style of anime as it is, though I am quite a bit more partial to the older portrait rendering of Janus.