The Texas court system ruled in the 1870s that only blades as such that are used by the military would be protected by the Second Amendment. Bayonets and sabers were permissible, daggers, sword-canes, and so on were not. Of course, that’s only a state ruling, not federal, and predates any modern rulings.
http://www.claytoncramer.com/primary/rkbadecisions/English1872.pdf