totally forgot to mention my thoughts about the watcher:
when someone learns enough about magic he becomes an avatar or dark avatar, or even a somewhat lesser great archmage. once you reach that state, you gain a freedom from age. i just think the watcher got to that state before any of the others did, and remained that way. if alric was born in his time its arguable he'd be just as old if he survuved to now.
point im trying to make is Bahl'al is a very powerful dark sorceror and therefore lives longer than normal people. he is human, and was born human, but just lasted a little longer than most other evil mages.
heron guards have a different kind of immortality, some kind of initiation ritual I'll not venture to discuss here... all i can say is that it is different because Herons are not archmages, i think just just cut it to be powerful mages.
-Welly