I've trained in many martial arts schools. There have always been one or two individuals that didn't know their own strength or who simply had some kind of mental issue that caused them to scare everyone else in the class who had the misfortune of partnering up with them.
And I'm not even talking about sparring. It could be a nice, smooth, flowing, stationary Taiji push-hands exercise where the object is to use as little force as possible to unbalance and get your opponent to take a simple step, never grabbing, never shoving, and never striking. And then suddenly you hear "thud" after "thud" on someone's chest across the room as they're obviously beating on someone, and you look over there and see some guy being thrown into a mirror on the wall. Seriously, this actually happened.
Well, the instructor needs to step in, take the offending guy aside, and explain that this level of force or intensity is not helping them, and that everyone else in the class is scared or angered by them. They should be given a second chance. But if they continue with their behavior, they should be tossed out and told not to return.
Often times, though, students are actually unaware of it. They don't know they're scaring or hurting others. Once they're told, they cringe and apologize. They didn't mean to be mean. And they improve from that point on.
On the other hand, others I've run into had this idea that martial arts training is supposed to teach students how to fight. So each thing they do in class is a kind of fight, with the same intensity and the same contempt shown for ones opponent. And they think everyone who doesn't play hard like them is just weak and shouldn't be training in martial arts if they have a problem with it. Like it's their job to show them the way of the warrior.
Those kinds of people are not easy to fix. They should be told that they're in the wrong school, and that they need to enroll in an MMA prize fighting school instead. After all, that's going to give them exactly what they want. And if they do actually go to one of those places to train and try to pull the hard core "warrior" crap with them, they're going to get beaten to a pulp.
As for Judo in particular, one thing an instructor should do is to sit the class down and explain to them that it's much better to lose to your opponent in class while trying to learn from it, rather than winning merely by forcing yourself on your opponent. The only thing you've learned in the latter case is that you were physically stronger than your classmate, which does you very little good. In the long-run, training without trying to force things will result in steady improvement.
My Judo instructor was a woman, by the way. She was a 5th dan at the time. She observed that female Judo students would learn the key concepts quicker than male students did, in general. And the reason she gave was that the males tended to want to compensate for their lack of skill by using their muscles to force things, whereas the females didn't have that option. Lacking muscle strength, the females needed to be more skilled in order to win. And so they "invested in loss" and learned easier and smarter ways of overcoming each situation.
Males can do the same thing, of course, if they're actively trying to be aware of their use of muscle power. Speed is still just fine. But powering through a technique is not. Using leverage, using positioning, using body mass, using timing and speed, all of those things are what you should be working on.
So if you're in Judo class, and you're rolling with a much weaker opponent, make sure you're not using more strength than they are. Make it a game. Make it a rule if you like. Or have your instructor make it a rule. Each partner needs to use only the level of force that the other person is showing, and no more, even if it means losing. This way, your wins will be more meaningful, and your losses will teach you something.
One other thing. You can extend this rule to every other attribute as well, besides just muscle strength. If your partner in class prefers to go slow and remain calm and analytical, you should go slow and remain calm. If your partner is a white belt, and you're a black belt, use only white belt techniques and skills they might have and nothing else. If your partner weighs significantly less than you do, try using only that much body weight against them. Don't attempt to smother them. Etc. You get the idea.
Hope that helps.