There is a decent university course in the United Kingdom's reaction to mid-80s Vietnam War
films; because the war had no negative connotations in the UK, movies such as 'Platoon' and 'Full Metal Jacket' were seen more as action films than social commentaries. 'Rambo: First Blood Part II
' was the most popular of the lot, a huge success in 1985, and it became fashionable amongst a certain cross-section of Britain's youth to own a 'Rambo knife'. Although there were officially-endorsed Rambo knives the budding British Vietnam vet
was more likely to purchase a cheap Chinese copy; these were often slightly redesigned versions of existing 'survival knives', with hollow handles containing compasses, matchsticks and so forth.
There were actually three Rambo knives, one for each film. Those for 'First Blood' and 'Rambo: First Blood Part II' were designed, at Sylvester Stallone's request, by Jimmy Lile, a respected knifesmith from Arkansas. They were similar, both derived from the basic Bowie design; the first knife was 14" long - 3" longer than the famous US Marine Corps 'ka-bar' - and unpainted, whilst the second was an inch longer, with a partially-blackened blade. This knife made much more of an impression with the viewing public, and was featured prominently towards the end of the film. Although 'First Blood' was popular, the sequel started off the craze. Both knives are still for sale and retail for around a hundred pounds.
The third knife was designed for 'Rambo III' by Gill Hibben of Kentucky, knifesmith and "official Klingon armourer" for Paramount pictures, no less. In line with previous form the knife was one inch longer still, a total of 16" with an 11" blade. Silver and stylised, it was very much like the film itself; large, expensive, ridiculous, but with a certain primal appeal. It is also still on sale - perhaps because the retailers over-ordered in the expectation that the film would be a huge success, which it was not - and is also worth roughly a hundred pounds.
Real-life special forces soldiers are generally free to purchase their own knives, although the SAS, for one, do not encourage their use, preferring silenced firearms. A shiny silver 16" bowie has no real practical purpose on or in the battlefield (a machete would be cheaper and lighter), other than as a bartering tool, or possibly a shaving mirror.