My memory of hero revival times is 1 hour plus 1 hour per level, max of 24 hours. This is confirmed in Travian answers.
An ally's level 94 hero died earlier today (on ts19), and had the expected 24 hour revival time.
But my level 169 hero just died (also ts19) and my revival time was only 5 hours and 17 minutes. Is this some benefit for a level 100+ hero or a random bug?
Edit: Just talked to another person with a level 100+ hero and his last revival time was ~9 hours. So it does seem to be decreasing with level past 100.