I often feel like fraud when I post on here as most of you are engage in combat, albeit very controlled and stylised, whereas what I do is as far removed from that as can be…almost like precision dancing. Thus I always post as a 3rd Dan in Wado Ryu Karate to alleviate my discomfort
Speaking as a HEMA practitioner who greatly enjoys messing around with swords, I understand where you're coming from. There are a few places in the world where people sometimes commit violence with machetes, but we have no way to recreate the experience of living in a world where the use of swords for dueling and warfare was commonplace. Nor would any of us want to if it were possible.
Theoretically speaking, it might be possible to achieve the skill of a competent historical swordsman. (Although not the skill of a master swordsman with significant experience in life-or-death battles.) Here's what I think that would entail ...
Practice based on techniques from actual historical sources from an era where swords were commonly used. (To avoid the development of technique that only works due to the vagaries of a particular competition ruleset or other simulation.)
Sparring/competition practice which rewards as closely as possible the techniques, tactics, and principles found in the historical sources. Every single sparring methodology I can imagine is flawed in multiple ways as a true simulation of real combat with blades. Therefore I recommend sparring under different rulesets so that hopefully the strengths in one method can help compensate for the flaws in another.
Cutting practice. This should move beyond the beginner stages of focusing on a single powerful cut from a static position and eventually include cutting a moving target and utilizing all the techniques which are in your technical repertoire.
Practice in quickly drawing and using the sword, a la Iado/Iaijutsu. If you can't deploy your sword quickly when attacked, you can't defend yourself with it.
Practice wearing a sword in its scabbard as you go about your daily business and getting used to all the various inconveniences and adjustments that requires. This isn't going to be possible for most of us in real life, but may be an option at some historical recreation events (although depending on the event the blade would probably need to be either a blunt replica or peace-bonded in the case of a live blade).
Practice fighting (sparring) in groups. Fighting in formation is very different from one-on-one dueling.
Study the various miscellaneous cultural and practical details that came along with the historical carry and use of a sword. This is an area where I suspect some of the koryu systems may have useful insights.
After all this, the biggest factor separating the modern sword practitioner from their historical counterpart would be the actual experience of life or death combat, of having someone try to kill you, of killing or maiming another human being, of seeing other people killed or injured by real swords. I imagine that a soldier with experience on the battlefield or a violent criminal might have comparable experiences which would fill that gap. I personally have no desire to invest in either path.
Then again, there were plenty of people historically who trained with a sword just in case or because it was expected of their social status but who never actually got in a sword fight. Since we have better safety equipment to train with now, it's possible that a modern practitioner might be able to surpass many of those individuals.
Fortunately, the odds of any of us ever needing to use a sword in a real fight are so low as to be practically non-existent. So we can practice for fun or for spiritual self-development or whatever other purpose we desire without worrying about having to test our skills against Fiore or Musashi.