Likely local smiths but there was also a Dutch production plant in Bandung (Java). They were producing the Klewang for the KNIL. The Klewang is a mix between a sword and a machete. Everything was available to produce swords even skilled workers.
@Bruce Pennington the picture of the mark is taken from a Dutch site.
https://www.marktplaats.nl/v/verzamelen/militaria-tweede-wereldoorlog/m2307382007-japans-officiers-showato-katana-1940-1945-gunto-stijl
@WillFalstaff You can use leather wax. I use a thin coat of petroleum jelly. Cheap and gives a good result. Used it for more than 40 years to preserve leather liners of German helmets.
@Bruce Pennington Hi Bruce,
I've been trying to find more information about the RAF soldier. I can only find one G.J. Southard, but without access to his service records, I don't know if this is the right person.
Regards, Ed
The latest addition to my collection. Old blade, civil tsuba and an inscription by a soldier of the RAF Regiment on the leather combat cover. G.J. Southard RAFR Malaya 1945.