Well, in Texas, a dagger of any length (AFAIK) is illegal, while a single-edged knife is only illegal if it is longer than 5.5". A dirk is in the same category as Bowies and Arkansas Toothpicks, a fighting knife longer than 5.5", ergo illegal (even tho Texas law doesn't per se define "fighting knives", it's easy enough to recognize them as such). I think a prosecutor would have to argue that you had intent to modify/sharpen that false edge into a working one, by the means that you were also carrying a sharpening stone or file "on your person", to sucessfully get you for possessing a dagger, even if it isn't.
(Just hypothesing here, pls don't bite my head off. We've all heard horror stories of overzealous prosecutors, even if it's the same story over and over.)
Matt P in Texas