In a more advanced style from my perspective the optimal way for heroes would be this:
The heroes in general should be rulers of all, like it was intended to be the best player in pvp originally. So a great way to achive that and to maintain it is to check players success. Most enchant on most used set, most attribute on most used set(which set can be defined as the set of the main class or even set by the player),castle ownership, clan hall ownership(with siegable hall bonus), clan level, amount of clan skills, clan rep contributed(all these ofc in case if the player is in clan or owns one), pvp activity based on k/d ratio and many more. Would be boring to write down all the stuff in my head. Than developing a point based system out of that and make the X best players on the server heroes until someone doesnt surpasses them on the imaginery ladder(you have more points than the 10th player you get hero status he looses it).
Altho your round based idea is a great thing too can imagine it is as an addition to the current system.