I enjoy a good story as much as the next guy. I am also a two-tour Vietnam veteran, 1969-1971. There were a few dispensations allowed for some officers, senior NCO's, and Special Forces types, but the rest of us grunts were simply not allowed to have, to carry, to import, or to export any personal weapons at all.

During my processing for shipment to Vietnam in 1969 I was relieved of my old Cub Scout pocket knife. I thought it might be handy (bottle opener, can opener, awl, etc), but the US Army classified it as an unauthorized personal weapon prohibited for US troops.

Going home in 1970 I carefully packed a captured double-edged dagger with wire-wrapped tang grip (similar to the WW2 commando daggers). It was confiscated before I was allowed to board the "freedom bird".

Going back in 1970 I carried my issued Camillus rigger's knife (switchblade clip point blade and hooked blade for cutting parachute rigging lines). No problem going in, but no way to bring it home with me months later. Government property, don't you know, and they certainly weren't releasing GI's onto US streets with switchblade knives.

I knew a few guys who sported custom knives, including a Randall or two. Tolerated in some units, but not in all units. Out-processing at the end of your tour usually meant going out through Cam Ranh Bay or Long Binh, and outprocessing included P-testing, gear searches, and generally being treated like criminals on parole before allowed to board a flight home.

End of first tour I took home a Belgian FN P35 (aka: Browning Hi Power pistol), captured in combat action, duly registered as a "war trophy" with all paperwork completed and present. Twice in Vietnam, and once in Japan, I had to call for senior officers to intervene to prevent my pistol and papers from being confiscated during security shakedowns. Missed one flight connection while demanding that my property be secured and returned to me. Threatened with arrest and court-martial several times.

Undoubtedly there were knives, pistols, and other personal weapons taken to Vietnam by individual soldiers and marines. The point I am making here is that this was not a commonly accepted practice, and loss of the item in question was always a daily possibility. Taking a knife with you, carrying it throughout your tour, and returning home with that knife? Maybe, if you were a staff officer or very senior NCO; otherwise highly unlikely.