Need some help with identification of sword

We recently bought a Japanese Officer's Sword at an estate sale. Per the auctioneer we were told it was a "bring back" or "war prize" that the estate owner brought back from his time serving in WWII in the Pacific Theater. The auctioneer said he had no reason to believe it wasn't authentic.

The blade shows wear, we can't make out what appears to be a hallmark without trying to clean it; but everything we read says not to try and clean the blades. So we are at a loss.. We love collecting WWII items. But, we tend to keep the US items and sell the foreign. We've had this for sometime but still can't confirm it's authenticity and want to give buyers as much information as possible.

Any help is appreciated. We seemed of have exhausted our research online..

Thank you in advance!

 

Nice katana cut to a wakzishi. Post it on the War Relics forum. someone will translate the hilt. Rich A. in Pa.

 

Thank you for the information