yep, there is still magic, or, perhaps they used oil tanned. For sure, stuff from late 50s on can be rough on fasteners and brass and etc.,on mine. Some is also going to be influenced by humidity. Corrosion needs an electrolyte, to include humidity, AND even the waxes and oils, plus any salts from many tanning processes.

Was not very clear in an above post, but it seems my leather-forever preservation efforts succeeded in one area, the leather, BUT, the oils/waxes magnified corrosive effects on fasteners and knives by providing a current flow path on the vegetable tanned leather, as well as lifting out more salts to surface.

And all of the leather commentary is not mine, but lifted from commentary by museum curators in their often fruitless attempts to prevent leather from deteriorating, as the destructive effects of salts on the fiber bundles is an attack on the inside, which no surface treatment can effect.

That sheath sure is a keeper if a knife to match.