Seems the tip is all that's needed. You're not gonna Highlander-slash anyone with a sword, much less a bayonet. Stabbing remains functional even if the edges are dull. I don't know if that's anything to do with the design, just my .02
There is nothing on it that looks like it would be a self sharpener. I don't know what kind it is, but the person who gave it to me said he got it from a British solgier in Iraq. I know it is not the AK-47 bayonet because I have seen those and this one is longer, thiner, has no serations on the back and no wire cutting attachment.
I'm not aware of any bayonet scabbard that has a sharpening device inside. Most scabbards have two long leaf springs inside that grasp the blade from the sides, holding it securely in the scabbard.
Most bayonets were not intended to ever be sharpened. A sharp bayonet is too prone to causing accidental injury and isn't more effective than an unsharpened one in combat use. Most sharpened bayonets were, unfortunately, sharpened by bubba, not in service. Sharpening lowers the market value of a bayonet by roughly one-third.
Exceptions include: Japanese Type 30 bayonets were often sharpened on the last half of the blade. The US M4, 5, 6, 7, series; the US M9; and the Soviet bloc AKM bayonets are all bayonet-knives, and have a factory edge of sorts. The Finnish M1962 Valmet bayonet is also factory sharpened. A factory edge on these does not impact value. However, additional sharpening puts them in the same bucket as other sharpened bayonets.