
Should I study “illegal” techniques?
Yes, yes you should.
Now to clarify a bit.
There are lots of techniques in the manuals that you won’t see allowed in modern tournaments (hence making them “illegal”). Some of these might be illegal purely as a tournament convention (i.e. no percussive cuts), some might not be allowed as they require a higher level of training than most competitors are likely to have (such as general grappling), and some are banned as there’s no way to safely do them at speed (looking at you, every master who tells you to break someone’s elbow over your shoulder). That said, you should totally study them.
In fact, you should study them even if your sole focus is on winning tournaments. Does your tournament scene not involve any grappling? Surprise, now you have an underlying notion of structure and can use it to more effectively move your opponent’s sword around. Did your opponent just do a bad thing and use a technique they weren’t supposed to? Now you know how to counter it and get out instead of relying on your opponent’s brain to process the word “HOLD”. Are you fighting on wet grass in the Atlantian five man and as your friend is charging you, you feel your feet detach from the ground? Congrats, you’ve just performed a perfect backwards shoulder roll and popped up back into guard.
In period, these arts were explicitly designed to kill people. Even though we’ve made going through someone’s abdomen with a finely-honed edge “safe”, it’s still important to study these arts as a whole and not just pick and choose which techniques we look at. Now, it is important to undertake take the studies of these techniques in particular in a safety conscious fashion lead by someone who knows what they’re doing even more so than with the rest of what we work with. That said, I highly encourage you to find such a person and broaden your knowledge base.
Also, learning this stuff is super fun.
This post are my thoughts after watching the latest Chewjitsu video, which you should totally watch here: https://www.youtube.com/watch?v=JDWf1qdy-w0