From a mechanical standpoint, the most important thing to add to a "Mounted warrior" class or subclass is some sort of mount symbiosis. Being on a mount should provide significant bonuses, and also some significant protections to the mount.
One of the weird things about D&D is that hit points escalate pretty quickly. A fighter will probably get about 7 hp per level, including Con bonus. But a war horse's hit points stay stuck at 19 - one good fireball and it's dead. That's one of the main issues with just using existing rules to build knights - there's nothing that gives the mount any survivability. So any mounted warrior class will need something to handle that, perhaps using the Beastmaster's defensive (but probably not offensive) bonuses to the mount.
But all of that ignores another important issue abut the mounted warrior, and that's that the typical D&D character spends a lot of time in dungeons and other environments where horses (and other mounts) are impractical. This is essentially a variant of the discussion we had about the ranger and what bonuses they should get for favored enemy and/or terrain - if those bonuses are significant in combat, they will either be overpowered in the right circumstance, underpowered in the wrong, or both.
I've always preferred hussar to cavalier...
what? ;p
But since D&D is fantasy, this could be any form of mounted combat and any culture. Sticking to just European historical definitions is a silly thing in a game with elves and mages.
One culture could have mounted archer knights modelled like Hunnic and Mongolian ones.
Another could have chariot knights with a squire steering and the knight chucking spears.
Another could have discovered guns but due rarity or expense, only the mounted knights used them.
And other would have giant warbeast cavalier knights with ballistas mounted on them.
But all that matters is the mount.
And the first answer that springs to my mind is status, rank, leadership.
In other words, I think what we're talking about here is the elusive 5E warlord by another name.
Disagree. What we're talking about is a Valor Bard with noble or soldier background. Maybe pick up heavy armor or mounted combat at 4th level. Or, start as a Fighter and switch to Bard at 2nd. Granted, it's a bit of a hack, but as elusive as the definition of "knight" seems to be, it's a lot better than spinning up a new class that would literally steal 90% of it's stuff from an existing multiclass combination.And the first answer that springs to my mind is status, rank, leadership.
In other words, I think what we're talking about here is the elusive 5E warlord by another name.
I'd rather see Warlord as a subclass of Fighter that works a lot like Eldritch Knight, but borrows from the Bard, rather than the Wizard. A Cavalier definitely seems like it would be a good Fighter subclass.Bingo! In reading this thread I was starting to think the same thing. Perhaps the Knight/Cavalier as subclass of Warlord? (The warlord doesn't seem to automatically assume skill or role as cavalry, but knights are almost always cavalry of some kind.)
This is probably the biggest argument for having some way to deal with mounts. I don't really want to see that restricted to just a specific class/subclass because I'd like the Hun Barbarian to be able to get roughly as much use out of his horse as the Cavalier Fighter or a dedicated Cavalier class.But a war horse's hit points stay stuck at 19 - one good fireball and it's dead. That's one of the main issues with just using existing rules to build knights - there's nothing that gives the mount any survivability.
And, this is the biggest argument against worrying about it too much for a standard game. It would be nice, though, if it got enough attention that there was at least a framework for improving mounts. Looking at the DMG for creating/modifying critters, my simple solution might be to have a feat that allowed a character to add hit dice to a specific mount based on the character level (basically, when the character is above the CR of the mount, the mount gets additional HD). I wouldn't worry too much about upping the damage, but could see an argument for something about once per "tier". Only one mount at a time can benefit from this (assume ongoing training) and possibly only when it was within sight of the PC (not sure about that -- leaving the warhorse on guard duty is a genre staple). If the character replaced his mount, he'd have to work with the new mount for, say, one week per level he was trying to bridge (7th level Bard training his warhorse spends 7 weeks). That's probably horribly broken in some way, but it's something.But all of that ignores another important issue abut the mounted warrior, and that's that the typical D&D character spends a lot of time in dungeons and other environments where horses (and other mounts) are impractical. This is essentially a variant of the discussion we had about the ranger and what bonuses they should get for favored enemy and/or terrain - if those bonuses are significant in combat, they will either be overpowered in the right circumstance, underpowered in the wrong, or both.
5th Edition already handled the Knight role will as a combination of Background and the Fighter class. If you find yourself getting a large number of heavily armored warriors into shock formation on horses ... well that's what rulings are for.
Knights, even in legend, were not exactly known for casting arcane spells every day. Perhaps singing or composing poetry or some other such accomplishment, because that sort of thing was expected of nobles, of course.Disagree. What we're talking about is a Valor Bard with noble or soldier background.
Warlords also not known for casting arcane spells. Not particularly into the entertainment industry, either.I'd rather see Warlord as a subclass of Fighter that works a lot like Eldritch Knight, but borrows from the Bard, rather than the Wizard.
That standard game is set in stone, so it's not an issue.And, this is the biggest argument against worrying about it too much for a standard game.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.