Nord should unlock the champion level quests today for the Argent Tournament. I've learned a few things about jousting in the game over the past few days, a few pearls of wisdom that might prove helpful to others.
At the valiant level, there are two quests that require mounted combat: The Grand Melee and At the Enemy's Gates. They work a little bit differently, so I'll do each in turn.
The Grand Melee
If you've worked your way through aspirant, you already know the basic abilities. But like most of these vehicle quests, don't presume you'll use all of them. Your best strategy in the Melee is to focus on only three abilities: Defend, Shield-breaker and Strike.
Before you even talk to an opponent to challenge them, bring defend up to 3.
When the fight begins, to hell with chivalry, you get a few brief seconds while your opponent rides away from you. Hit them with a shield-breaker and then ride after them. DON'T CHARGE. It's not worth it, especially given how you keep riding past them after the hit. You want to keep to point-blank range as much as possible.
While in point-blank range, spam Strike. Eventually, they'll try to move away to set up a charge. Shield-breaker and close the gap quickly and then repeat spamming Strike. Refresh defend periodically so that it's timer doesn't run down. The fight won't be over quick, but you will take them down.
Situational awareness is important. There can be 5 or 6 other jousts going on at the same time and that makes this quest live up to its name of "Grand Melee." But that can also lead to confusion. On more than one occasion, I've lost my opponent in the fray, which often gives them the leeway to get away from me and charge me to death. Try not to let that happen.
This one can seem intimidating at first, since each of the lieutenants has a retinue of about 5 footmen. But it's not as hard as it looks. There are also the commanders, which look a bit like lieutenants but are larger and have a full 3 stack of defend on them. You take them down in the champion version of this quest, but avoid them for now.
The Scouts are designed to a be nuisance and little more. Their lightning attack does very little damage, but it does remove a level of Defend with each hit. Tag them with a shield-breaker twice and down they come, but refresh Defend once you're done.
As for the others, find a lieutenant and charge them. Charge appears to have an area effect attack of some sort, because often times I find I ride down and kill the footmen while attacking the lieutenant. Be careful to reign in your charge once you overshoot. It's very easy to aggro additional mobs if you don't. Spam strike while in melee range, keep defend up, and you'll drop these guys quickly. Same goes for any footmen who survived your initial charge.
Watch out for fast repop. With anyone and everyone trying to do these quests, it's very easy to be rushing towards a lieutenant group in the back row only to have groups repop on top of you. Fighting 2 or more lieutenants plus 10 or so footmen is bad. If they dismount you, pray you're playing a class with an aggro dump, because you will not solo them normally. For me on a warrior, all I can do is stand there and let them kill me.
Edit: Champion Level Battle Before the Citadel
Basically the same quest as Enemy Gates, only upgraded for Champion level. Now you get no credit for the footmen, but have to kill 5 lieutenants and a commander. If you're working through valiant for another faction, this quest overlaps with it.
Commanders fight like the valiants back at the tourney camp and are defeated the same way. However, note that every time the champion pulls away to charge you, odds are good following him is going to aggro more mobs. Footmen are a minor nuisance, just ride over them. Shield-breaker scouts fast, since they'll make you very vulnerable to the commander's attacks. I suggest fleeing if you pull a lieutenant.
Now that a lot of folks have hit champion, the whole zone is a serious clusterfuck. It ain't much fun to try to kill 5 lieutenants when 10 to 20 other people are competing for them. Same for the commander. Lots of kill stealing. Repop is super-fast, which can get you in over your head real fast. Nord died twice today trying to complete this quest because of that.
FYI, I've not done the "challenge the champions" quest at the camp yet. I've not decided if I want to try it yet. Considering the chaos that this whole event is degenerating into, I doubt I want to. I'm torn. Claymore of the Prophet is seriously sexy.