Sad but true. Mana spells specifically mention foci as being able to be targeted by them and foci are stated to have an astral form when active (which is why weapon foci can hit spirits and projecting mages at all).
That's pretty jank, but there's no interpretation of the rules where it isn't how it works. I could see houseruling it... Since I honestly couldn't see a situation where an astrally-projecting mage is aware of an adept with an active weapon foci that they know is the enemy and not trying to disable that, since the adept can't do shit in return.
With an assensing roll you could know the target has an active Weapon Foci and no active spells on themselves or other foci... Then you just manabolt the foci to hell while floating 90 feet above the ground so the adept can't hit you with it even if they have Astral Perception.
I guess though, this situation is to awakened as street samurai and hackers are to mundanes. Get your buddy mage to be watching the astral and have them to blow up any projecting awakened trying to kill your foci.
