Gerber Mark II fighting knife.
The ordnance knife during the Vietnam War was the Kabar, introduced in WWII and useful for both combat and field usage. Because of its dual function, many soldiers felt the need for something more lethal, along the lines of a real and proper dagger. A dagger in the true sense meaning something longer, narrower and, most importantly of all, that had a double-edged blade.
That in fact is the reason why the most successful knife used strictly for combat in the Vietnam War was, by far, the Gerber Mark II.
Although it was never officially issued and therefore had to be paid for personally by the soldiers, it nevertheless became so widespread and ‘fashionable’ among them that it came to be a legend of the Vietnam War.
The LRRP (Rangers' Long Range Reconnaissance Patrols) were – and currently remain – the only elite military unit to use a real combat mission on enemy territory as part of their selection process. Only upon completion of his first real mission on enemy soil, was the rookie accepted into the LRRP and, to celebrate, was given a Mark II as a token for his new status as a true military scout.
The Mark II therefore came to symbolize the whole unit as, in many ways, the Randall 18 came to represent Trautman's men.
A great part of the recognition enjoyed by the Mark II was certainly due to its menacing appearance although this recognition wasn’t always well received. It even appeared in the hands of anti-war activists while they marched in protest as evidence to the world of how American soldiers had reached an all-time low wielding such a 'vicious' kind of weapon.
Some of Trautman's men owned Mark IIs as well, but they only carried them on missions when the offensive use of edged weapons was assured (or when overall equipment weight wasn’t an issue).
As a knife, the Mark II was 'superior' in terms of pure offensive power but its narrow blade made it useless as a field knife.
Thus, for both Baker teams, the 'Baker knife' (the Randall 18) was the most important among knives anyway, and even more so on long-range missions, when equipment weight was of the utmost importance so soldiers would only carry one knife, that being the most useful one.
The only soldier who carried a Mark II on each mission was Coletta, keeping it on hand and ready to lend either to Rambo or Delmore, when the two 'shadow men' had a silent hit to do.