Kdtyjb

Not possible without also ejecting particulate matter. If it could be done then people would be cut into pieces by standing near a helicopter or aircraft propeller.

The only solution would be to use sand or shot blasting. Even then, if your opponent was wearing armour, the worst you are likely to do is clean it for them.

You would also require quite a lot of equipment.

A metal cutting water jet shoots at 760 m/s you could attach one to your sword.

Speed of sound 343 m/s if your character arm
can move that fast? Then there is compressed air in a air gun. (why not just use throwing weapon or a gun)

As pointed out in the adjoining replies, a blast/slash of air cannot occur on its own, from a physical viewpoint. You can either compress that air and direct it at the target and this would require insanely high precision to focus it and cause significant damage. Also, as the other reply states, "air slashes" are basically shock waves travelling in air. Now, from my knowledge of undergraduate fluid mechanics, a shock wave occurs when a fluid is made to undergo a careful transition from subsonic state to supersonic state by making it flow through a convergent-divergent nozzle. In order to create the shock wave at the exit plane of the nozzle (which literally is your weapon), you need to operate it very precisely under the "third design pressure ratio point" which, in practice, is too difficult to achieve. Also, once the shock wave exits the nozzle, it can no longer be treated as a one-dimensional wavefront, rather it becomes three-dimensional, expanding and dissipating exponentially. So, that would require your opponent to be present within a few meters of your reach.

It is possible to kill with air pressure, you just have to be REALLY CLOSE to do it

The only documented death I found from "air pressure" is Jon-Erik Hexum, who was bored on the set of his tv series. He had a gun loaded with blanks, and decided to play a fake game of Russian Roulette with his gun and the blank cartridges (i.e. put the gun on your temple and pull the trigger).

This is still not safe because of both the explosion created by the blank and the bits of paper and plastic moving at high speeds out of the muzzle. He died from a fractured skull and pieces of paper and plastic that were embedded in his brain.

Blanks cause injuries if put next to the skin.

Of course, millions of actors have been "shot" by blanks with no ill effects. Most on-set fatalities involved a malfunctioning or poorly maintained gun, such as Brandon Lee.

To sum up - It is completely possible to cause injury or death with air pressure, but the death zone is basically touching the other person. Anyone with a sword could simply cut off the hand holding the "air sword", so this weapon would be completely impractical.

One other thing to consider. Blanks are meant to be a safe way to fire a gun on-screen. Real bullets came first. If you have the tech to get air moving at the speed required to injure or kill, you already have the technology to make a real gun that fires lead projectiles.

A wind with maximum sharpness is a discontinuity - where the velocity suddenly changes between different regions of aim, rather than continuously (gradually) changing from one velocity to another.

I don't know how dangerous air shock waves are, but water shock waves can klll you underwater. Probably, a sufficiently strong air shock wave (i.e. large enough change in velocity) will be as deadly as you want.

Shockwaves are commonly spherical, heading out in all directions from a point, but I think some directionality must be possible, just as sound wave and light waves can have some directionality. Perhaps, originating from within a pipe?

However, a shock wave generated by a sword slashing (extremely quickly) would travel laterally to the sword - like the bow wave of a ship. A force-push (extremely quickly) might work better.

disclaimer all off the top of my head, not an expert

No, its not really possible.

Sound is just a pressure wave. If you have a powerful enough sound wave, it can do some damage.

Loudest possible sound wave is 194 decibels. This is a result of the wave trough being a vacuum (and the wave crest being 2 atm.)

This sound level is considered approximately the level required to be fatal. Human studies are necessarily restricted. It is thought that this sound level could induce fatal embolisms in the lungs.

Since flesh has considerable flexibility, it is resilient against sonic assault. Something rigid like glass or concrete would be more easily damaged, and can in fact be destroyed when a frequency closely match to a natural vibration mode is used. This is not a sonic cutting attack though.

194 Db is not powerful enough to cut flesh. So, you cannot use a cutting sound strike no matter how you wave your weapon. In theory, if your weapon was large enough, and moving fast enough, it could be sufficient to cause damage due to hearing hearing loss, or even a stunning effect, but never cut flesh.