Whether in an urban or natural environment, some form of fixed-blade, full-tang, non-folding survival knife is a must – and a knife without a sharpener is almost as silly as one without a sheath, since you might find yourself using for all kinds of rough jobs in an emergency. Here are some of the best and worst options generally, as well as some specific suggestions that span the spectrum from short and sweet to strong and serious.
Survival Knife Don’ts: Some knives seem sleek and suited to the task, but end up being just the opposite – here are some types and models to avoid. Skip the cheap hollow handle mod (which can store small gear but break in a pinch) or the too-cool ballistic or butterfly knife (this is not just a weapon). Likewise, there is no need to go to Rambo-scale with this tool – if it is bigger than you will carry, it will not travel with you when you need it the most anyway. A folding knife or multi-tool can be a handy addition to your survival collection, but save that for a later date (more on why in a moment).
Survival Knife Dos: Full tang is a must – the steel should extend all the way through the handle so there is no chance of it snapping off and leaving you holding a plastic hilt. This is why a multi-tool or folding knife are poor alternatives, even if they are more compact and multi-functional respectively. Something that has an easy boot or belt strap, or can be otherwise attached on the outside of your clothing or gear for easy access is ideal. There are a number of Army, Navy and Air Force knives that fit the bill nicely, as well as a variety of hunting, wilderness and other outdoor-intended possibilities.
Survival Knife Specs: So, the ideal survival knife is solid steel, easy to access and … what else? It varies from person to person, but for most folks a blade length of 3.5 to 5.5 inches is probably ideal, erring on the thicker side to keep it from breaking as well. Long ones are tempting, but less handy in general for this purpose – even shorter would likely be fine too. Thee seductive teeth of serrated knives can be a temptation too, but they are not as useful as they look, and are a good deal harder to sharpen (sometimes reducing the sharp area by 30 to 40 percent or more). Shoot for a straight and solid blade, well-weighted and (for saltwater use in particular) stainless or at least rust-resistant.