Hello Oldschldude,
the blade from the Luzon sword in up I've cleaned with sandpaper only, by such a rusted blade you can start with 80 and can end with 1000 to get a nice smooth finish but know people which go higher.
Your barong blade don't seems to have bad rust so I would start with 120 or 160 paper. I bet that your blade will show lamination, look close to the spine if you can see lamination lines.
I wouldn't clean such a blade with any sort of acid like pineapple juice, the blade will get a grey/dull surface and it will need a lot of polishing to get it away again. The sandpaper you can use dry or with oil. Before you start to etch a blade clean it with aceton to remove all oil and grease.
Thank you for the compliment.
Best regards,
Detlef