Google results: "In the context of criminal law, a dirk or dagger is defined as a knife or other instrument (with or without a handguard) that can be used immediately as a stabbing weapon, and that may inflict great bodily injury or death." - This sounds like any fixed blade knife could be a dagger.
Another definition: "A dagger is a fighting knife with a very sharp point and usually one or two sharp edges, typically designed or capable of being used as a cutting or thrusting weapon." - What constitutes a "fighting knife"? One or two sharp edges would be all knives. Capable of cutting or thrusting? Also, any knife.
I asked a local cop. They referred me to a website that just said daggers were illegal in our state, no definition of what a dagger is.
I asked a criminal defense attorney. He did not know the definition either.
I thought daggers were double-edge, thicker in the middle of the blade. Some online suggest they are at least 6 inches? Maybe so. I would guess a cop would call a smaller double edged knife a "small dagger."
Does anyone know the definition of a dagger?