Okay - you are not dumb enough to walk around with a PC 12020 weapons. But, are you smart enough to train for knife fencing with a folder? I have to say, not many Filipino drills, for example, center themselves around the folder. But, let's say you school does. So you have your folder, and you are attacked by a real criminal with a knife - a real dirtbag - whoops, he doesn't care about the law, that is why he is a dirtbag. He had a PC 12020 knife - dirk/dagger. His draw is way faster than yours - whoops, did you work on folder against a straight knife in your knife fencing school. Oh, you didn't, you are dead - ambush percentages lie with the illegal weapon.
The legal systems do vary from state to state. And yeah, I agree, sometimes a DA can be a real pain. But, as for the above, check out our school website. It has some vids on it:
We train in a variety of knives, weapons, situations, tactics, and yes, we get into legal aspects. It helps to have an instructor that has a LE background.