I've never injured myself putting a slip joint knife away.That being said I don't trust them as a potential emergency defensive weapon... heck I don't even really trust liner lock knives in emergency defensive situations, only tri-ad locks or axis locks (or their variations).I do have one edc knife that I carry that is a liner lock but I've trained myself to hold it in such a way that my fingers don't get in front of the path of the blade in case the liner were to fail in an emergency defensive situation. It's less than ideal.I should also add I don't trust slip joints or liner locks for heavy field craft such as batoning. I'll thump on a tri-ad or ram lock but I prefer a fixed blade.
I am always at a loss to understand the role of a pocket knife as a defensive weapon. Any folding knife is about as poor a weapon as you can get. When that mugger pulls a knife and demands your wallet, are you under the misguided idea you will have time to grab for your folding knife, and then get it open before you get knifed??? And if you do by some stroke of luck get your knife open, are you ready to engage in a knife fight with some idiot on drugs? If you need a weapon, some sort of blunt force truma weapon is far superior to the folding knife that you may not have time to open. A club of some sort is easy to have around, a stout walking stick, pool stick, a nice master lock with a bandana through it, bicycle lock, and lots of other items. Stone breaks knife. Not to mention pepper spray. When I went through the police academy, we learned how a blunt force truma weapon is effective immediately when bones are broken, nerves smashed. There's a reason police are issued sticks, they work. And as far as batoning with a folder, That's a good way to break what may be your only cutting tool. They make unfolding knives for combat use as well as survival, called fixed blades. They work really well for heavy duty use and you don't haver to worry about them folding up on you. A pocketknife is for those zillion little jobs that come up. Way back when I was growing up, men carried a pocket knife. If they went hunting they carried a sheath knife. When I was in the army and we went to a little fracas in Vietnam, we got issued the Camillus MK2. A nice sturdy 7 inch fixed blade. But I used my SAK at least several times a day for all those little jobs that outnumber the big ones by a 50 to one ratio. There's two kinds of knives in the world, those that fold and those that don't fold. If you don't want to worry about your knife folding, don't have one of those.
I am still trying to get over my fear of using SAK knives, even though I know that they won't snap on me. I have cut myself but that was because I swiped the knife at one of my fingers.