*Sucks in a breath.* By god this thing took me a long time to do. Five hours...O_o. Anyway, not sure if this is actually appropriate to put on DevArt, but I think it's art, damnit! The Butterfly Knife is a very artsy weapon...
Anyway, this being a How To weapons tutorial it does indeed need a disclaimer.
This tutorial was intended to explain the art of the butterfly knife so that it may be used for display only. This is not in any way intended to teach people to fight with said weapon, nor do I endorse using it for violence. This is soley for the art related aspect of the weapon.
Before attempting to perfrom anything with a weapon you should be well-aware of the consequences and dangers involved in its use. A Butterfly Knife IS a weapon, and therefore should be handled with maturity and sensibility. I, as the author of this tutorial am not responsible for any injuries you may inflict upon yourself or others while practicing with a weapon. It is your responsibility to keep yourself and those around you out of harms way. I strongly recommend putting electrical tape around the blade, or purchasing a blunted knife. This way you will decrease the chance of hurting yourself while practicing with it.
Please be careful, handle the weapon with responsibility. Use some common sense, if you think something you're doing might hurt you or others, DON'T DO IT. I am just the passer of knowledge, I've given you fair warning, if you get hurt the blame does NOT rest on my shoulders.
OK, disclaimer over, onto the lesson!
First things first, always always ALWAYS hold the handle WITHOUT the latch. If your holding the latch, then when the blade is flipped, the sharp part will come down onto your knuckles, and if you're swinging it with a particular force, IT WILL HURT.
The tutorial itself is fairly self explanatory. Follow the guiding pictures and arrows. Check often to make sure that the blade is pointed in the proper direction as indicated in the photos. If your not sure about a certain flick, move the blade with your hands first so that you know where the sharp end of the blade will be once momentum takes over. Walk yourself through it a couple of times, and after lots of practice, it will look cool.
The steps sometimes seem a bit counterintuitive, but this is only because that once the blade is moving quicikly the repeat steps allow the hand to change grip without stopping the motion of the blade.
Once you get REALLY good you can control the flicking with momentum itself, and it won't even touch your hand.
It's really quite an impressive skill, I hope you all enjoy!