Let's look here:
First, every kitchen has knives that aren't obviously weapons the enemy might get upset about, so why would you drop them crappy daggers? (NOTE: It also wouldn't matter if they were "Sterile and unmarked," because enemy action is enemy action.┬á Having "US" on the blades wouldn't change anything. These aren't marked, because they were never made under a military contract.)
Second, every workshop can make its own crappy daggers, so why would you drop them crappy daggers?
Third, if they already have ball bats and, you know, guns, why would you drop them crappy daggers?
Fourth, since there were discussions of dropping guns, why would you waste resources dropping crappy daggers?
Fifth, some sellers reference these being "dropped by the OSS in the Philippines."┬á Virtually every adult male in the PI has several variations of bolo and machete, so why would you waste resources dropping crappy daggers?
Sixth, it takes 10 seconds with Google to determine MacArthur refused to let the OSS operate in the PI, so how would they have dropped them crappy daggers?
Seventh, in no nation the OSS was purported to operate do we find these mythical "drop knives," nor, in fact, do we find the guns they dropped, because they didn't drop any knives, and damned few guns.┬á By the time the Liberator pistol was made, the Free French had enough real weapons.
Eighth, a bit more research will show that these were made by Foster Bros, from old Trapdoor bayonets, and sold cheap to servicemen, and their families who shipped them overseas, if by chance the serviceman didn't have a decent hunting knife, because crappy daggers were thought to be of use, but rarely were.
You will find some "experts" confidently stating these were "OSS Drop Knives," in order to sound authoritative, but none have ever produced a purchase order, an op plan, any evidence of any kind, or any extant examples from the areas in question.
So, when you see any dealer confidently talking about "OSS Drop Knives" or "Drop Bears" or "Drop Playing Cards," you can assume he's either incompetent or dishonest, and not buy anything from them.