Due to all the edits and clarifications asked I will re write the question tomorrow, thanks for your patience. Leaving this up until then, for reference.
In the setting I'm working on, magitech has created, among other things, a class of weapons called "projection blades". When such a weapon is activated, it allows the cutting edge of the blade to interact with distant targets as if it were touching them. Essentially you swing your sword at a training dummy 15 meters away and you cut it just as if you were right in front of it.
While the effect itself is invisible, as in, you only see a person swing a sword and something distant getting cut, you can visualize its dynamic by imagining that the effect is projected in a straight line parallel to the blade up to a certain distance (details pending, but for the purpose of this question let's say up to 50 meters, the exact length being adjustable ) and in that area it "bridges" the distance between the edge ofthe blade and whatever object ends in the way, for the purpose of touching and therefore cutting targets. This effect doesn't have any other physical properties and therefore can't be used, for example, like a lever. It's therefore optimal to trigger the effect at a specific point during a swing, as to avoid interaction with unwanted objects. This is possible thanks to a trigger on the handle. To reiterate, the blade itself doesn't physically change in any way.
The effect moves from the blade to the target almost instantaneously, but this still means that an object in the way of what you want to cut will still partially or completely block your cut. Parrying and deflecting can therefore still be a thing, especially whith another projection blade.
The effect only transmits force, which is why you have to be moving relative to your target or swing in order to do damage. You can't just point the sword directly at your opponent and pull the trigger to impale him like with some kind of infinite length lightsaber.
Some energy is lost when you use your weapon this way, meaning you would hit harder with the actual blade rather than with the projected force effect. Obviously the convenience of turning a melee weapon into a ranged weapon at will more than makes up for it.
Force travels both ways, so your feel your weapon impacting with the target and you can potentially get it stuck, however this is quickly remedied by just turning it off.
Edit for additional details:
The "projection" can only be sustained for a very little time, details to be decided but let's say it's slightly below an entire second. This is more then enough time to strike and do damage.
After triggering the effect the magitech device needs to wait a moment before triggering again. Again, details pending but let's say 0.5 seconds. This seems like a small amount of lag but in martial arts and actual fighting I think this would make the weapon less "spammable" and encourage a more precise and deliberate fighting technique.
Given the dynamics and limits described above, what would be a plausible fencing style for users of this kind of weapons? Specifically for duels between projection weapon users.
- Forgot to mention that in this setting most armor and shields have been made obsolete by other kinds of weapons, creating something like the late 18th century in terms of tactics and equipment. This means that while armor and shields would probably be really effective against projection blades, they simply aren't around anymore and duels take place between unarmored opponents.
Edit 3 with yet more contextualization:
- The weapons are used mainly due to their unique advantage scaling really well with user skill. If you are a good sharpshooter, you are still bound by musket-like weapons that can't fire more than a few shots per minute, but if you are a really good swordsman with a projection blade, you can defeat several unskilled opponents before they can even touch you, and be precise and quick enough that opponents armed with these early guns would actually find themselves at a disadvantage. This means thar the weapon is seen on battlefields mostly as a status symbol for officers and decorated veterans, and in civilian use as an implicit statement "I'm using a weapon that requires more skill, beware". So duels happen more due to matters of honour or reputation, like cowboys in the far west and samurai in ancient Japan. While there are surely more formalized contests between swordsmen, like academias and the like, the focus of the question should be on duelists of a more spontaneous kind.
Thank you and forgive me if the question is unclear in any way, this is my first post.