The navaja was popular among thieves and the Spanish "Gypsies", the Gitanos. The navaja's popularity among the criminal element is attested to in James Loriega's book Sevillian Steel. Loriega writes, "Navajas crossed the hands and drew the blood of soldiers and sailors, rogues and ruffians, and diplomats and aristocrats both in and out of Spain's borders. The use of the navaja fostered a mystique, not only from Seville's back streets, but also from the seedy waterfronts of Barcelona, and the cosmopolitan promenades of Madrid. Regardless of their original intent, the navaja represented the ultimate means for resolving disagreements, misunderstandings, and problems that arose in dockside bars, darkened alleys, and an untold number of places not found in any guidebook; places where there is little reliance on legal recourses; places where you either catch a glimpse of steel and live-or miss it and never know why you died."
Comments on the above:
The Navaja is a traditional Spanish folding working/utility knife & the larger bladed knives could be used as a fighting knife. This style of knife is quite different compared with the other traditional style, mostly known as "cuchillo de monte" (field knife) which is used mainly by hunters. The etimology of the word is derived from Latin ("novacula") and the concept of this tool comes from XV century and the barber's knife. After more than 2 centuries of popular and continuous use (1750-1950 approx.) navajas slowly became both quite smaller and less popular. Nowadays is carried by a minority of the population and as a strictly utilitarian tool.
This knife is not a flick knife or a switchblade, but a folding lock knife, however, with much use, the unique cog wheel locking system, would sometimes become very worn & slick, thus allowing the blade to be opened & locked out very rapidly by a flick of the wrist (much like a bali-song or Phillipino butterfly knife) utilizing centrifugal effect. This distinctive "crack, crack crack" of the blade opening gives this type of weapon another nick name of cra/cra/cra in Spanish.
The larger versions of the navaja would traditionally be worn pushed into the belt or sash with its distinctively curved handle left exposed, handy for rapid deployment. The navaja would have been carried by anyone who needed a knife, seamen & shepherds as well as bandits & guerrillas.
The blades come in all sizes & shapes, but the most common is of a modified bowie type with an unsharpened false edge (the clip blade) about 4 to 8 inches long. Most knives have a wooden or bone handle reinforced with steel or brass, although they can be purchased today finished with very expensive materials such silver, ivory & gold. There navajas exist with blade lengths of 2 & 3 feet, but these are purely for ornamental display.
Examples of ratcheting and non-ratcheting navajas may be seen at http://www.knivesofspain.com