Hi Louie,
My dad and I sold nice holsters for 32 years at gun shows as a hobby. I do not store anything metal in leather. Too much of a risk.
It doesn't matter if it is high-end leather or cheap, it has the possibility to ruin metal. You never know how leather was tanned, how it was dyed, how it was treated, and how it was finished....or if someone rubbed some concoction into the leather. If the holster or scabbard gets in moisture, the leather can absorb that and hold it to the metal along with chemicals. I have seen waaaaaay too many guns ruined over the years due to storage in leather. I've had folks ask to buy a holster, and when asked the purpose, they'd say "To safely store it in". I would always dissuade them.
Worse than that is any eggcrate foam padding. That stuff is the devil's work. It soaks up moisture and holds it to the finish.
I do not trust cloth against metal, as it too can absorb moisture and hold it. Why risk it? My knives live outside their sheaths unless they are in use.
I have found that wax paper is a good surface to store metal items upon, as it does not absorb moisture. It is also great inside a zippered gun rug, as it keeps the oiled metal and cloth apart.
Just my experience. God Bless, Marc