I've been told for 50 years never to store my knives in their leather sheaths, and in all that time I've never had a spot of rust on a blade. Only problem I've had was the green crud forming on the brass guards. Which is a pain in the neck to remove, but is not a serious issue.
I'm thinking Saran Wrap might be a solution to the greening issue. Brass only turns green where it contacts leather.
