AbdulAlhazred
Legend
The feat is actually Weapon Focus [Staves] since you pick a weapon group, not a particular weapon. It should work since if you are using a staff implement as a basic magic weapon, it's still a staff and, thus, a member of the staff weapon group.
Yeah, I would hope so. A weapon is a weapon, and a staff IS a weapon. I agree with you CubeKnight, it is perfectly reasonable to use that logic. Just try to explain it to a player. Most players are not rules gurus and their brain just melted out their ear.
So in the name of sanity, I don't treat magic weapon staves any different from magic implement staves. If I don't want PCs using a Cunning Staff as an implement, then I don't give out Cunning Staff as treasure. Overall that is probably the simplest solution for any of that type of problem, just avoid the few edge case items. I wouldn't give out a Grasping Tratnyr either (that is an ugly one, a pole arm that can be thrown, brrrrrr...).