I get that question a lot. "Hey, is it possible to learn sword fighting without a teacher or school?" Sometimes it is not even a question but an statement, "You can learn sword fighting by yourself!"
The short answer about self-learning sword fighting; You can not effectively learn it, and you do not learn it properly.
I think the first real question is, why do you feel the need to learn by yourself?
I have heard a few arguments, for example, that there is no dojo nearby. Some people say to me, "I have no money," or "I can't travel to Japan." and "I just do not have the time." These are all real reasons, but still not one that should be preventing you from learning correctly.
The internet with its ease of access and bevy of information conditions us that with a click of a button we can ingest information and learn something new. That is true for many things. There are, however, significant limitations when it comes to something like sword fighting. If you want to learn something, you must go and learn it properly.
I have used the phrase "learn properly" a few times. Learning how to use a sword by yourself is not a proper nor a safe way to learn. I have never tried learning the sword by myself. Indeed, I have, though, tried to figure things out by myself with a lot of training all ready accrued. I am not sure of this allure to learn samurai sword fighting or martial arts alone. Honestly, it does not resonate with me.
Lots of moving parts
Certainly, the desire to learn something does resonate with me., however, learning something as complicated as swordsmanship without a teacher does not. I would instead want to get a significant amount of sword fighting knowledge from a teacher.
With over 20 years of experience teaching people, I have seen the problems that exist. Even teaching people directly is full of difficulty. You can continuously show someone the correct posture or form, but they just do not get it, even with direct manipulation of their limbs. Learning directly under someone's supervision takes a lot of time and work. Doing it on your own with fewer resources is a folly that no martial arts teacher should encourage.
If someone thinks they are going to have a more fruitful time to learn without direct feedback, they are in for a rude awakening. Learning without the input (physical and verbal) of a good teacher is not the best use of your time. It is also inviting physical injuries that could be avoided with proper training.
Posture is important. Proper posture in martial arts cannot be gained well from self-learning. Posture can be copied in a static form to a certain extent. You can even wind up copying someone's movements. Without the expert eye of a teacher to point out the weak points they will most likely elude you forever. Your movement and kamae (stances) will be forever marred with weak points. There is also a danger of developing poor musculoskeletal alignment and usage. That can lead to not just ugly and weak forms but injuries that could have been avoided with correct training.
Within the framework of posture comes how we hold our weapon. In sword fighting each school has their own idiosyncrasies, but there are some common things to avoid. Grabbing this or that technique for here or there is a real illness that I have seen often with the YouTube warriors. They watch various schools and how-to videos from different people. They jam things together and come up with their own ideas. To be fair people do this in real life as well. I call such people dojo-hoppers. They flit from teacher to teacher or school to school and cram their minds full of information. Back in their lab, they assemble Frankenstein budo. It is some extreme hubris to think without any real and substantial training that you would be able to make up or interpret sword fighting techniques.
Learning too many styles at once is also a danger, but I will save that for another time.
It is hard to keep all the movements and postures (including how we hold the weapon) in mind and not fall into bad habits that do not just make our movements look sloppy but translate in a very real way into "unrealistic" or inauthentic sword-fighting moves. Swinging a sword from over your head and cutting downward seems simple. It is not easy to do efficiently and properly. There is a lot more going on than meets the eye.
The stubborn among you will likely ponder this and still think that you can move on and do it alone anyway.
Drop the ego.
Really, just drop it. You can not, and I have never met or heard of a teacher in martial arts suggesting anyone can, just pick this stuff up and learn by yourself. There are so many little details that we must be aware of. Books and videos are a nice resource but they are not the primary place to learn something so alive as samurai sword fighting. It sounds strong, but the attitude that we can learn techniques of swordsmanship without a teacher is just wrong. You can learn something, but it will be very incomplete. It just easily becomes an excuse to never get involved with a real teacher and school. Whatever you teach yourself will be a very pale shadow of what someone is learning from a competent teacher. I do not want to discourage anyone from learning martial arts. I do, however, want to discourage bad ideas that just lead to a waste of time and increase of personal injury.
Patterning your own movements with your teacher is great, and part of the learning process but that takes a long time and a lot of adjustments to get the movements down. Getting to a satisfactory point takes a lot of time and correction from a competent teacher. Time means years, not days or weeks. Watching a video over and over of a random video on the internet is not going to teach you something useful in the end.
You can certainly teach yourself the parts of a sword. You might be able to hone a skill a little here and there when you already possess some knowledge. The problem is books and videos are not really for beginners, they are beneficial for more seasoned practitioners, and a lot more can be mined from such a resource once you have proper basics.
Knowing about certain sword fighting ideas on an intellectual level is good. However, it does not stop there. There is a lot more to learn experientially. Your teacher with experience in training and teaching has a lot of information to assist you along the way. I do feel the teacher is vital in learning martial arts because its best to be part of a particular system and not a mish-mash of styles.
Learning by yourself is a superficial way to get information. The way martial arts are passed down through history effectively is not in a superficial way at all. Deep learning is how it has been done. Those that tried to do it all their own are not in the history books at all. Sorry, Musashi did not teach himself how to fight with a sword either. I have not come across a historical figure that did teach themselves everything.
Again, I feel we have to ask ourselves why the insistence for learning by ourselves? Learning from a teacher is a critical part of the process to acquire a martial art like samurai sword fighting techniques.
There is a lot of efficient and inefficient movements. Some schools as well might differ quite a bit. What's ok in one school might be considered verboten in another. You can not mix and match this and that and mash it together although it is done all the time by many. In the end, you are left with something that has no soul or skeleton to it. Its a bag of mush really, just as we would be without such things.
Nutmeg in a recipe, just a little goes a long way.
I wonder, is it a matter feeling insulted? Are you humiliated in some way about your intelligence? Does it feel like someone is offending your intellect when they say you can not self learn samurai sword fighting?
If that is the case, then again, drop the ego.
It is not about that, and the sooner you lighten the grip of your ego the better. That thing just makes a mess of stuff in martial arts. A little ego is ok but too much is going to spoil your life and training.
You should not feel that you are stupid or less of a person because you need a teacher. Teachers, when they are good, guide us and fill in the missing information. Actually in any school, martial arts or math, it is the same. We are doing a lot of self-learning all ready. However, we need the guidance from the teacher. Not to mention when we want to learn that cool new sword move, well they are the ones that hold that information. It is not in books, nor on Youtube.
The other aspect of practice is your mind. Were you aware of the ratio between physicality and mentality in the martial arts? I like to say that martial artists are more mental. Jokes aside, it is true that bujutsu requires a more mental component than a physical one. In the beginning, it is certainly almost all physical. Later in training, the psychological and spiritual take the greater spotlight.
Our teacher has experience of what's going on in the mind during the techniques, and this information is even more important than where your toes are pointing. Reaching these places by yourself is hard. There is a lot of physical and mental chaos that comes from a sword fight. A multitude of things is happening that you can not without experience be observing by yourself.
Do not be afraid to learn with a teacher. Sure grab a book or watch a video as a supplement to your training. Train with a teacher though, as they are more valuable than any other resource around.
Johnny Yuma Was a rebel; he wandered alone.
Going off on your own when your skill is mature is indeed a conventional part of the process though. When the time is right then, you will be off on your own figuring things out. That is natural. You will have plenty of time for that pure self-learning experience later in your training. Likely days will come when you will miss having that wisdom across from you in the dojo.
It is not that you can not learn anything. You can learn something, but a piece of a puzzle, while something, is not the whole picture that you are trying to piece together.
Don't be in a rush to learn something like sword fighting by yourself. Find a decent teacher to guide you and lay out the information in a proper and orderly way that facilitates efficient and safe learning. If you want to learn, my advice is to find a way to do so with a proper teacher.