The basic idea of military knives for survival comes from the Fairbairn-Sykes fighting knife WWII, a knife that was used by aviation.
The Fairbairn-Sykes has been used for a multitude of tasks, to combat, but also as a field knife. This knife was in the shape of a dagger, with a double-edged blade and a design that modern survival knives do not use anymore.
In essence, a contemporary survival knife is a knife hunting updated, able to withstand extreme use and is also more versatile. The double edge design was abandoned, and also its main function is changed from a combat knife to a multi-purpose tool.
Steel Recon Scout SK-5The best survival blade must be able to handle a multitude of tasks (among which also the self-defense), so we must choose the knife carefully.