I don't recall all the Paladin lore information off the top of my head - there's probably a Sounsyy post somewhere that provides far more enlightenment than I could ever provide - but I'll try to provide some general tidbits.
There are currently two "types" of Paladin that are known. The first and most recognizable are the Sultansworn, they are the Paladin order that basically serves as the Secret Service/Special Agents for the Sultanate of Ul'dah. They serve as her most elite guards and also safeguard a number of artifacts and secrets. Playing as one shouldn't have too many difficulties, age or no, considering Papashan is a well-recognized Lalafellan Sultansworn who is getting on in years.
The second is a slightly more recent concept: the Free Paladin. These are basically Paladins who are not tied to the Sultanate. They go out and about, using their abilities in accordance to their own codes and whatnot. The Job Quests, as you may recall, result in the WoL becoming one of these. If you want a bit less political turmoil and more freedom of movement from a literary standpoint, you'd probably want to be a Free Paladin. Even if it's a newer idea, there's nothing keeping an older Sultansworn from deciding his abilities are of greater use elsewhere and embarking on this path.
I'd provide some more information, but you character concept is pretty threadbare beyond "old and a Paladin." Do you have any ideas for what kind of story you want for him? Where he might be from? Or even just the kinds of characters you enjoy playing most so we can see about helping you creating a Paladin you'll enjoy RPing as.
There are currently two "types" of Paladin that are known. The first and most recognizable are the Sultansworn, they are the Paladin order that basically serves as the Secret Service/Special Agents for the Sultanate of Ul'dah. They serve as her most elite guards and also safeguard a number of artifacts and secrets. Playing as one shouldn't have too many difficulties, age or no, considering Papashan is a well-recognized Lalafellan Sultansworn who is getting on in years.
The second is a slightly more recent concept: the Free Paladin. These are basically Paladins who are not tied to the Sultanate. They go out and about, using their abilities in accordance to their own codes and whatnot. The Job Quests, as you may recall, result in the WoL becoming one of these. If you want a bit less political turmoil and more freedom of movement from a literary standpoint, you'd probably want to be a Free Paladin. Even if it's a newer idea, there's nothing keeping an older Sultansworn from deciding his abilities are of greater use elsewhere and embarking on this path.
I'd provide some more information, but you character concept is pretty threadbare beyond "old and a Paladin." Do you have any ideas for what kind of story you want for him? Where he might be from? Or even just the kinds of characters you enjoy playing most so we can see about helping you creating a Paladin you'll enjoy RPing as.