There's no hedge knight player characters in BM. Going by the only definition of the term I could find, which seems to come from GoT and refers to an unlanded knight; all knights in BM have estates.
The noble characters in BM are the creme de la creme of noble society, the most known of all nobility. There are no 'unknown' player characters. Information about them is collected and distributed throughout society/BattleMaster. Unlike those nameless NPC nobility. If duels were meant to be restricted to between certain ranks, we would do so, so perhaps there is a good reason they are not?
To be fair though, it's perfectly possible to have noble characters in game who don't have any estates. Sure they should be able to challenge any other noble to a duel but why on earth should they expect the other person to accept?
