Currently, all soldiers have Soviet’s NR-40 knife. However, as well known, almost all countries had own knifes for soldiers. Also, in case of other equipment like shovels, TNTs, porches and binoculars have each unique models.
Therefore, I suggest to add unique knifes for German, American, British, Italian and Japanese to replace NR-40.
Note: I don’t know well about military knifes. If you know more information please post in replies please!
German
When the start of WW2, German soldiers had old WW1-era knifes but later they were replaced by new knifes. I think Infanteriemesser 42 would be suitable for game.
Close combat knife / Nahkampfmesser
Germans standard combat knife used during WW1. At the start of WW2 lots of soldiers still used it.
Infantry knife M42 / Infanteriemesser 42
German infantry combat knife adopted in 1942. Also known as “boots knife”.
American
I’m not sure which is better. If possible, it is good to add USMC Mark 2 combat knife for Pacific war and add M3 trench knife for Normandy.
Mark I trench knife
Old WW1-era knife.
USMC Mark 2 Knife, Fighting Utility
USMC’s multipurpose combat knife adopted in 1942. Also known as “Ka-Bar”.
M3 trench knife
American combat knife adopted in 1943 to replace WW1-era Mark I trench knife. Equipped by paratroopers, rangers, and soldiers who do not have bayonets.
British
I’m not sure what knife ordinally soldiers had.
Fairbairn–Sykes fighting knife
British fighting knife adopted in 1941. Mainly used by elite units like paratroopers, commandos etc.
Italian
M1939 fighting knife
I can’t find information about it a lot.
Japanese
Japanese did not had dedicated trench/combat knifes, but they had several knifes.
Considering to combat purpose, perhaps 30th year type bayonet is better.
Knife / 小刀
Japanese standard small foldable knife with can opener. All soldiers equipped it.
Total length was about 70mm and blade length was about 50mm.
https://sabive.iku4.com/sonomamazyan/日本軍、陸軍%20小刀%20ナイフ
30th Year Type bayonet / 三十年式銃剣
Japanese standard melee weapon used during WW2. All soldiers armed with it.
Normally, length of blade was 400mm but length of edge was 190mm because it was designed to lunge enemy. However, in frontline soldiers often sharpen it to expand edge from point to guard by the affect of Japanese traditional swords.