I've suspected what Anaris is saying, based on what I've seen of heroes in the past. Characters become legendary, and if they die as a hero, well they were already legendary, and indisputably a hero (because, dead) well then they're a legendary hero.
Legendary status I believe has to do with a couple factors. Prestige is definite. Titles, factor maybe some, but I've seen folks spend their careers as Knights and become legendary. Possibly something to do with the number of people they've met too. Hard to be a legend if no one knows your name.