If you look at the list of weapons :here, you can actually find that there are scabbards.
Admittedly, the mechanics for it seem rather clunky. But as far as I can tell, if you grab a sharpened scabbard (it has an edge on the outside), then you do not actually need to take any feats to use it (assuming martial weapon proficiency). ...I think.
The regular scabbards seem a bit more complicated though. It is listed as an improvised weapon (which wouldmean you need Catch off guard), although the fact that it has a weapon entry seems to indicate to me that it can be enhanced like a normal weapon.
Because the original question has been answered, I guess I will hijack the thread by asking how do these mechanics play out.
Nope. I can at least get a handle on that one.
Separate weapon entry, so different items. You need to get weapon focus (combat scabbard).
you don't have to take peneties with a combat scabbard
dont forget you dont need to attack with your scabbard; Equipment trick opens up a lot of options