Well, for starters, they use training weapons. These are are weapons that are essentially what they’d be using and are blunted. The character gets the effect of training with the weapon and practicing their techniques against another opponent without risk of fatal injury.
This is a long standing practice in all martial disciplines and it is much safer than letting beginners murder each other. You never get to touch a real sword until you’ve reached the end of your training. They’re expensive, dangerous, and most knights aren’t going to have the money to replace all the weapons they’ve destroyed during training.
You start with wood, then move up to metal, then move up to the real blades.
You also don’t have your knights learning to joust each other with real lances either. It’ll be blunted lances like the ones used at tournament, and will use those at all times except on the battlefield. They’ll only be allowed to joust other students when their performance is satisfactory, and they will practice with a dummy first. They’ll keep practicing with that dummy for the remainder of their existence, because it’s safer than practicing with another knight and they can fine hone their skills. Then, they move up to a hanging ring.
They don’t just put you on a horse, thrust a lance in your hands and hope for the best.
They’ll spar with padded armor. When they reach a point in their training where the time has come for them to wear armor, they’ll be using older suits rather than new ones. If they spar with live weapons at all, at any point, the rules of the duel will be to first blood and will be watched very closely by their training instructors.
Training happens in stages.
You practice the pieces of the technique, broken down. You learn the stance, then you learn what you’re doing with your hands. How to hold the weapon. Then, you learn how to move the weapon. Then, you practice the technique all together incorporating your whole body. Then, you practice that singular technique with another human (drilling), then, you learn other techniques, then you learn to connect all those techniques together, then you learn the defenses against those techniques, then you practice them with your partner, and then… then you spar.
In between these stages, you condition. You drill. You condition more. Drill more. Learn more techniques. Sparring becomes a reward. As you go up in rank, the targets you are allowed to hit in sparring expand. The more difficult techniques you learn. You may then advance to other weapons, or you’ll be doing most of them at the same time.
Round and round we go.
Practice with the sword before you hold the shield. Practice with the shield before you hold the sword. Learn to wield the sword with one hand. Then with two. Then with a shield. Learn horseback riding. Learn the staff. Learn the bow. Learn the knife.
Then, once you have a base and you are lucky, you will spar against different weapon types.
If he is confident in your abilities and you have the time, he may hold a melee or allow you, his trainee, to participate in one. Or you may do so while squiring to a knight, depending on your master. What is a melee? It is a practice battle, like a real one without the death (usually).
Or, you may not get any of this. Be thrown into battle up front and be forced to learn as we go.
There’s a target point for what you want to have, and then there’s what you get. A medieval knight or squire or even a page may very well be forced into battle long before they’re “ready”. A page’s training also depends heavily on who is fostering him/her and if they care.
Knights were not given the same training. The concept of training, armed warfare, and mass conflict as we understand it today didn’t exist. They were dependent on which local lord took them under his wing, funded them, and how invested he (and his arms master) was in their training. If they got a sadist for a teacher then they got a sadist for a teacher.
The problem with the romantic “live weapon” idea most people have is that “live weapons” will better prepare you for real combat. They don’t, because nothing compares for real combat. These characters may also see combat long before they become a knight, as they’ll be squired out first and their experiences depend on what their knightly master will be doing.
Knights are a training investment of fourteen years. You don’t waste that lightly. It also costs way too much to outfit them with real shit that they will then misuse and break. Especially not when you can just give them the sturdier, more reliable shit that many others have used before them.
The same is true for the horses. They get the training ponies with the hard mouths before they ever approach a warhorse. They need to prove themselves worthy of the substantial investment which comes with equipping them.
Yes, even the sadistic masters do this. The only difference is the mind games they play while it happens.
And, yes, with the first battle it will always be “hope for the best”. Anything else, they’re kidding themselves. Training is about getting you as prepared as you can be for the real thing, but it is not the real thing and no amount of live blades in a practice arena will change that.
Which is why you don’t do it.
Besides that, there’s the injury risk. Students who don’t know what they’re doing have a greater chance of injuring themselves and others. Injuries are costly. Training relies on consistency. If you’re stuck in your room with a twisted ankle, a bruised collarbone, nevermind a serious injury like a broken bone, then your training will lapse. A student needs to stay active in order to remain viable. If they’re not then its a waste of money, equipment, and other resources like food.
You’ve got to feed them, billet them, and everything in between. If you want shock troopers that’s what the peasants are for. A knight is an investment. You push your investment. You do not break them. They then repay you with their service.
A single soldier in the United States Military costs the taxpayers around a million dollars. Their training is also among the cheapest things the military can buy. In terms of resources in the Middle Ages, the feeding, training, and equipping of a knight costs far more than that.
Think about it. And maybe do some more research.
Otherwise, you’ve got a trainer going, “I want to blow through fourteen years and nine million dollars to soothe my students’ egos!”
“Anything Goes” is a Hollywood creation. You train all combatants on the assumption they’ll be killed, you want to give them the tools to survive but they’ll probably die. For this reason, you need every single one. You can’t waste them on each other. That’s a major reason why tournaments came to exist, so you could have the war and the skill without the death.