I would imagine it would depend on the power of the wielder of the Force Weapon in comparison to the Daemon. In the chase of Ghargatuloth, he's one of the most powerful Greater Daemons to ever enter realspace. Quite possibly THE most powerful. I'd imagine, that with a strong enough psyker, and a strong enough force weapon, it could be possible to even kill him permenantly. But the way things are, the Imperium probably has no one even close to being able to do something like that. Let alone a Force Weapon powerful enough to get the job done.