Why would you think this?
Feel like I probably already answered that in this post:
https://forums.shadowruntabletop.com/index.php?topic=27492.msg500494#msg500494You merely get a -2 to actions on the physical plane.
You can still
sense a gray and shadowy mirror of the physical world while in astral, but trying to do
any actions in the physical world while only using your astral perception (rather than your normal 5 physical senses) is highly distracting (which is why you get a negative dice pool modifier of 2 dice to
all your actions in the physical world and you can't even use your physical perception at all).
It is far less distracting to for example be in AR with your matrix persona link-locked in a host and engaged in cybercombat by multiple IC and a security spider while you take actions in the physical world (you don't get a negative dice pool modifier at all, but in in some cases a GM might rule that you get a negative dice pool modifier of 2 dice to your physical perception).
They still have to physically swing their sword...
...you still need reaction and intuition to dodge because you are still moving your meat body out of the way.
To be honest I am not even sure you need to physically "swing your real life sword" or move your real life body "out of the way" while engaged in combat with an astral entity...
"You think that's air you're breathing?"Anyway, what we do know is that fighting wholly astral beings is mostly a mind battle. You are basically fighting invisible "ghosts". The only way you can even sense them in the first place is by shifting your physical perception to your astral perception. The only way for you to hurt them (or being hurt by them) is by shifting from your physical perception to your astral perception. You need to dip into the astral world. Different rules apply here. Things like physics and momentum are no longer a factor. Being skilled with a weapon or in martial arts are worth nothing. Being physically agile or strong will not benefit you in astral combat. Even good Reaction will not help you. You use Willpower to land your attacks, Charisma to deal more damage and Logic to avoid getting hit. For your physical skills and attributes to matter you need to have a real target. A target with an actual physical form.