I'm deeply sympathetic to your desire to avoid losing expensive equipment. Yes ... it hurts when gear gets lost. But it's always worth spending some cash on a good knife. And folding knives are very handy - cuz' you've always got one on you.

Remember what those SAS blokes (commando's) in England like to say ... "You're only as sharp as your knife". Unless, of course, you are Bear Grylls. In that case you can always eat a member of your camera crew if you get really hungry!!!

Anyway, back to the knife ...

* No holes in the blade (forget it!)

* Partially-serrated blade is nice

* Blade length 3-4 inches is good for survival, blade length 5-6 inches is better for defense

* You can probably buy a good used folder from your local pawn store - there's a lot of gear on sale now that a recession is happening. But stick with good knife brands, and check the action & locking of the blade carefully.

Most outdoors people carry a knife.
But few know how to use one really well.