Mr Ghostface said:
GE Predator:
I believe that I can explain that. For 19 years, Luke and Obi-Wan lived on Tattooine, a desert planet with two suns. My theory is that those who are not native to Tattooine may experience some excessive aging over a period of years due to the two sun. And as we know from the prequels, Luke and Obi-Wan were not born on Tattooine.

Works for me. After all, look at Owen and Beru. Those harsh Tatooine desert winds and blazing sunshine "is doing murder to mesa skin".

Other than the joke about Luke's age, I was not referring to age as in appearance. I meant in physical fitness. Dooku certainly looks even older in the PT than Obi Wan does in the OT, yet Dooku is a seriously athletic duelist while Obi Wan looks like... an old man who someone handed a lightsaber and said "see that guy in black? Try to beat him up with this."

Keep in mind I'm not talking about the limits of the actors, or CGI heads on young bodies, but the characters themselves. I don't think two suns would make Obi Wan lose his skills over time.

As for the idea that he was out of practice, I want to make a counterpoint...

Shaolin Monks, no matter how old they get, keep on practicing their martial arts, not because they want to keep up their practice for fun, but because it is their culture, their way of life. I've always assumed the Jedi are supposed to be very similar to this (the use of temples, training from youth, etc.) So, despite having the temple destroyed and being chased off into hiding, wouldn't Obi Wan continue his practices as a Jedi? After all, it is his culture! On a remote planet, in the privacy of his home, why would he not be able to practice Jedi techniques, both physically, spiritually (or with the force, in this matter), and mentally?

But none of this really matters, since ANH has been filmed over 30 years ago, and the Obi Wan duel we got is the only duel we will ever get. Only Ady's re-editing has made him appear faster.