You mean this thread?
From how it’s been described, the event system should have something akin to this – there was an example of a knight being challenged to a duel. It’s just not been impemented yet, so we’ve no clear idea on how it works in practice. :P Could be that they’re planning for the battle the be fought through checks and have it only take place in text, or they might have an actual fight take place.
You’re called someone’s ‘second’ if you could stand in for them when dueling. They could do something with that like have it be a part of a questline where some noble wants to hire you to fight a duel for him. Lose and your man, win and you piss of the other noble with more quests as a result.