There are not many classes in D&D that focus on defense. Usually defensive prowess is obtained through feats, items, and spells; not the class itself. The knight from Players Handbook II seems to be the exception to that, with a plethora of options and abilities focused around keeping himself and his allies safe from harm. There is certainly a role for this type of character in most parties, especially if there is another warrior type to really focus on dealing damage. I also like that there is a class that is the archetypical armored and mounted warrior that does not have the rigid moral and religious code of the paladin, though the knight does have his own code that he must adhere to.
The basics of the class are a pretty nice assortment; full Base Attack, d12 Hit Die, 2+ skill points, and a good Will save. It seems a little better than the standard array for martial classes mainly due to the d12 and that the one good save is Will, which is probably the most useful save to have and will cover up for the low Wisdom that the knight probably winds up with. The skill list is fairly typical, the only notable exception being Knowledge (Nobility), but the knight probably won’t have too many skill points to spread around.
Many of the knight’s abilities stem from it’s Knight’s Challenge class feature. Usable a number of times a day equal to half the knight’s level plus their charisma modifier, the challenges available to the knight increase as they gain levels. By yelling out to opponents on the battlefield the Knight is able to get an edge for himself and his allies. One of the best aspects of the Challenge is that it is always used as a swift action, making it very easy to find spots to apply it and still being able to take other actions. The fighting challenge allows the Knight to mark a target, granting them a +1 to attack, damage, and Will saves against that opponent. This increases to a total of +4 by 19th level. It’s an okay ability and it gives the Knight the luxury of focusing on defense with their feats, knowing that they can fall back on the fighting challenge for a little offensive boost. Other challenges give the Knight the ability to draw enemies to them, give allies a chance to reroll saves versus fear effects, reroll a failed mind affecting save, cause weaker opponents to become shaken, and continue to fight for a little bit after going past -10 hit points.
At 2nd level the knight gets Mounted Combat as a bonus feat, which is pretty much feast or famine. If you plan on fighting from horseback than it is obviously an essential feat to have, however if you don’t it really has no uses at all. The thing is that it is going to take a bit of work to make the knight a good horseman, so I’m not sure how useful it is. For starters it is going to be based on Ride, which the knight has very few points to spend on. And Ride is Dex based, another area that the knight is going to be deficient in. As a DM I would have no problem allowing the Knight something different here. My suggestion? Combat Expertise. That’s a great feat for the Knight, for both mechanical and flavor reasons it fits the class really well. Due to the Int 13 requirement the Knight may never be able to obtain it otherwise, so I think it’s a good option. The other 2nd level ability is shield block. This gives the Knight an additional +1 shield bonus to their AC against one opponent. It is essentially Dodge with a shield. It increases by 1 at 11th and 20th level. Not a bad ability but it sort of dictates the style that the knight is going to be using in combat, making them a sword and board type of warrior.
At 5th, 10th, and 15th level the Knight gets a bonus feat that comes from a list. Most of the mounted feats are on the list so the knight can continue to pursue that, though it’s a long time to wait for some of them. I think that you would probably want Spirited Charge before 15th level if that was your thing. The list is not the greatest feats in the game, but there are certainly enough viable options than any Knight will wind up with something decent. Vigilant Defender (also at 5th level) is sort of a nifty ability. Any Tumble checks to avoid attacks from the Knight have the Knight’s level added to the DC.
My favorite Knight ability is Shield Ally, obtained at 6th level. As an immediate action Shield Ally lets the Knight take half the damage dealt to an adjacent ally, making him an excellent flanking partner for a rogue or any other hit point needy friend. At 14th level they can absorb all the damage to an ally, though they are limited to doing this once a day.
At 17th level the Knight gets the bizarre Impetuous Endurance. The fighting spirit of the knight is so great that he no longer fails a saving thrown automatically on a roll of one. Really? That’s a 17th level ability? They may not automatically fail, but they will probably fail anyway. A 17th level Knight has a base Will save of +12. Let’s give him a +1 Wisdom, and assume that he has Iron Will (which is on the bonus feat list). We can even say that he has that feat that uses Cha for Will saves instead, so let’s make that a +4. That is a +18 Will save, with the rolled 1 that is a total of 19. I suspect that most casters fighting 17th level characters are going to have DC’s higher than 19. And the Fort and Will are going to be even worse. Totally stupid ability. They have such a remarkable fighting spirit? How about a reroll on failed Fort or Will save instead? That gives them a more realistic chance of actually using the ability.
If I was making a Knight I would put my best stat into Con, followed by Cha and Str. Shield Specialization also seems like a good feat for them, or anything that can jack up their AC. If they can get Combat Expertise, Improved Disarm or Trip also seem to be good options. I can’t imagine that there is a better “tank” class among the melee classes in the game. Lots of hit points, a shield, defensive abilities. The Knight is really a support character, their job is to keep the squishier characters alive while they sneak attack or cast spells. It also mixes well with the Dwarven Defender, making the ultimate in party protection. One of the best aspects of the class is that all the Challenges and the Shield Ally ability are swift and immediate actions, so the Knight can still go about fighting, moving, or whatever else they want. Their best features don’t seem all that powerful, but when you consider that they are essentially free to use (action wise) it makes them much better.
The other interesting feature of the Knight is the code that they must adhere to. All Knights have to be lawful, but they also have to follow a code of conduct. The description talks about honor and being righteous, but the end of the entry spells out exactly in game terms what the code means. Sort of an interesting approach to controlling conduct, but it seems to work. Knights may not gain a flanking benefit in combat, though allies they are flanking with still gain the +2, Knights never attack flat footed opponents, and they never deal lethal damage to helpless foes. I like it. None of them are crippling to the Knight, but they have enough substance that it’s not a total throwaway. The flanking one is the biggest disadvantage, since Shield Ally means they will frequently be in flanking situations.
I would put the Knight on par with the better melee classes in the game. It can fight a little and has a ton of survivability, and the moral code makes it good for roleplaying. I think that my biggest complaint is that most Knights are going to resemble one another. They are all going to be horse riding, shield wielding, damage absorbers that greatly endear themselves to their teammates. You can do worse.