You sir are not only an idiot, you're a monumental idiot and you'd likely shit your pants if you even saw somebody holding a knife. A knife is NOT a defense weapon. It loses to a gun, a baseball bat, a stun gun, a can of mace and a guy throwing rocks. And it's not even a proper defense against another person with a knife. A "pro" would drop his own knife and go empty hand against an attacker with a knife because that's the easiest way to disarm somebody with a knife. Knife fights are for movies.
I'm sorry to tell you this, but you don't know what you are talking about. You don't know the person you are responding to, nor do you seem to have the slightest idea what a "pro" would do, just stop.
You can say the average Joe Sixpack does not have the intestinal fortitude to take an edged weapon to someone (justified or not) and you'd be right. But your little run down on their effectiveness couldn't be more wrong, sorry.
I get the impression you have not traveled much, nor have you had to deal with much violence (that's a good thing!).
Do you not know many cops? Bouncers? Ever traveled to South America? Philippines?
Now I can't speak for all of them, but going on my experiences and study a "pro", when faced with a determined and imminent edge weapon threat, will turn tail and beat feet if possible. A tactic that everyone should adopt. If not possible, the blade he carries is not for show, and will be obscured until a fight-ending cut can be delivered.
Show me a guy who delights in menacing people with a blade and I'll show you an idiot destined for the hospital, or morgue. You don't advertise what the opposition can use against you: the reach of your weapon, whether or not it's sharpened on both sides, if there is a pommel to worry about, etc. You certainly don't drop your weapon and embolden the aggressor into thinking he's got the upper hand, sounds like you're the one hitting the movies too hard.
I don't understand the appeal of balisongs, never have. Showing off manual dexterity may be what someone is going for, but I'd rather have a piece that was safer to use, sturdier, and a lot quieter and less flashy to operate. If OP is happy with it more power to him tho...