I don't think I have ever clicked on a name from the Legendary Hero burial message and seen a character with less than 100 honor. That makes me think it is something that gets accumulated.
I would think that legendary part of the hero has more to do with prestige than honor- nothing to do with the time spent as hero, or accumulation or battles. Just the pure H/P values. My own legendary hero had 111 honor and 27 prestige at death. So I am going to say that to be a legendary hero you need to have 25 prestige. Perhaps 100 honor as well.
