Gentlemen, thank you for your further comments. As far as the age of the blade is concerned, the retired officer this belongs to has told me that his father, an officer in the USMC, recovered this sword from "within the cave system" on Iwo Jima during the battle for that island. Like yourselves no doubt, I would normally be inclined to take such an account with a pinch or two of salt(!), but in this case I would not.
So, the Japanese officer who carried this sword presumably felt it was a sword of at least enough merit or significance for him to wear it.
I mention that in case it has any bearing on your evaluation of the sword. I'm aware of course that swords have been misrepresented or mistaken in Japan as well. In fact, due to the cultural inhibitions against open disagreement or contradiction, I suspect it may have been quite an easy place to do so, but of course that is just my conjecture.