When shaving every possible ounce of weight out of your pocket or pack is really essential, nothing beats the Baladeo 34 Grams Knife ($35). Made from 420 stainless steel, this diminutive blade is true to its name, weighing in at a scant 34 grams — 1.2 ounces — all while packing in a locking system and integrated belt clip.
Here's yet another essential to add to your zombiepocalypse toolbox. The Gerber Gator Machete Pro ($55) was designed with zombie killin' in mind — you can see it in use on The Walking Dead — and as such features a multi-purpose blade that can be used as an axe, machete, or knife, a grippy rubberized handle, a military nylon sheath, and an included sharpening stone to keep it ready for action when you're on the move. Oh, and you can also use it for clearing brush, chopping through branches, and other more mundane tasks.
It's not exactly a switchblade, but it's as close as you're going to get while staying on the right side of the law. The Benchmade 581 Barrage Knife ($220-$235) offers an AXIS Assist locking mechanism that helps you get the blade out in a hurry when it's needed — such as when fighting off rival gang members angry flocks of chickens — and a reversible pocket clip to keep it handy. Available with a plain, ComboEdge, or black-coated blade.