If killed by most people, the demons are just sent back to hell. Presumably the same with angels.
However if killed with an angel sword, the demons die & are gone. As in ceased to exist anywhere in any form. Like when Barbiel killed what’s his name in the DC church yard.
No afterlife, since they were already part of the afterlife. Presumably the same thing if a demon kills an angel with a demon sword.
I’d also bet normal folks would not make it to the afterlife if killed with a demonic or angelic blade, but they may not work against anything BUT angels & demons.