Any sort of sheath will tend to hold the moisture if you put it away damp, and this will lead to corrosion. It is even worse if the sheath is made of vegetable tanned leather, as the leather contains sulfur, due to its being largely protein, and during the tanning process, leather is treated with both acids and bases, which tend to remain trapped in the fibers.
Two of my other hobbies are collecting cameras and leather craft. I always cringe when I found a camera that had been stored in a leather case for years. Usually, no matter how dry it had been stored, atmospheric moisture had caused corrosive fumes to be released into the camera. As a result, the meter and all the other electonics were usually bad, and the brass under the chrome finish on the camera would have green verdigris pinpoints all over it.
I do have and greatly enjoy making and using my leather camera bags, but I never store photo gear in them.
An outdoor tool, such as a Lesche or Predator, ought to be, In my opinion, kept stuck in a bucket filled with sand with a drizzle of motor oil in it, as was suggested earlier in this thread. Just my opinion.
HH,
John Morton