I BELEAVE THIS FORM WAS IN USE WELL BEFORE WW2 AND IS STILL MADE IN LUZON. THE ONES WITH PHILIPPINES, TREES AND GRASS SHACKS ON THEM AND OFTEN A DATE AND LOCATION WERE MODIFIED TO APPEAL TO THE SERVICE MEN AS SOUVINEERS. THE ONES I HAVE SEEN ARE FUNCTIONAL JUNGLE KNIVES/ FIGHTING KNIVES NOT JUST POORLY MADE SOUVINEERS.
AT ANY RATE THEY WERE BROUGHT BACK BY MEN WHO FOUGHT IN A TERRIBLE WAR FOR THEIR COUNTRY AND MANY OTHER COUNTRYS IN WW2 SO ARE OF HISTORICAL AND FAMILY VALUE.
AS TO THE PM ON THE BLADE I WILL HAZZARD A GUESS. AS OUR BLADES AND MANY OTHERS HAD MADE IN THE USA OR USA PERHAPS THEY PUT PM (PHILIPPINE MADE)