I've recently been tinkering making sheaths for one of my Damascus hunting knives, something I've noticed with a few is that if the blade stays in the sheath, dry, for a time (about 4 weeks) the blade starts to rust pit. Is there a way to prevent this, lining maybe, or sealing the leather with something? I don't want to start lining with kydex, seems a metaphorical slap in the face to the leather.
Any help greatly received.
I've been using veg tanned leather, dyed inside and out with oil dye, then sealed on the outside with mink oil.
Attached are pictures of said sheath and blade. The pitting seems to have stopped since I've heavily oiled the blade several times and put it in and out the sheath a few times.