I don't mean this as a feature of lock down either. I am talking about a separate arena. I leave it to you for collaborated ideas on how it would work though. I figure this would add a ladder match system to the game (if it was added already then I obviously did not know that).
The most I can figure is that you would get to use a lance, I am unsure about how it would work beyond a timed thrust. I also figure that the 'noble steed' would have a charge attack of its own.
Again, I feel others should expand on this one as I don't know what it would take to implement or how rewards would be distributed.