I quite liked the style of the sheath but not really the material - although I shouldn't really be using a leather sheath ...
Sheath materials are very much a mater of personal taste unless there are serious climatic considerations. Jonathan might not want to use leather in a rain forest for any great length of time because so many things like to eat it, but for carrying these blades around -- you shouldn't really store any blade in its sheath -- then leather is perfectly OK, and more readily available than woven man-made fibres in some parts. I like man-made materials and I like leather too, I don't much care which it is for most things but for larger tools I tend to prefer man made over leather. I think it's just what I've become accustomed to.
Curiously, stainless steels rely on oxidation of the steel for their rust-resisting properties. When there's enough chromium in the alloy it will react with oxygen to form a very thin, continuous and hard oxide layer on the surface of the steel. This layer self-heals in free air (20% oxygen) if damaged. That's what we call a stainless steel. Unfortunately if oxygen in sufficient concentration is excluded from the surface (for example exhaust gas may have very little oxygen; and simply placing something in contact with the steel may have a similar effect) and if there is moisture and especially if chemicals like acids or chlorine are present (e.g. bleach or common salt, even in fairly weak solutions) then corrosion can set in surprisingly quickly. Some stainless steels are more resistant to this 'crevice' or 'poultice' corrosion than others. Some, like 304 (or 18/8 or whatever else they call it, the stuff they make a lot of table cutlery with) are rather prone to pitting in these circumstances. A thin layer of oil or grease on the steel will prevent most water-borne chemicals from reaching the surface but will still allow oxygen to migrate through it to heal any scratches in the oxide layer.
I find that the larger the tool the more intensively and less frequently I tend to use it. So things like machetes might be used all day long for a few days and then stored in the workshop for weeks or sometimes months. If I'm concerned about corrosion on the tools then before I put them away I wash and dry them, spray them with 3-in-1 or WD40 and wrap them in an old cloth. Then I either hang them up like a saw or lie them wrapped in the cloth on a shelf, on top of the sheath if they have one. Before I started to do this I had one or two stainless blades which suffered from spots of corrosion because they were stored in the sheath, even when it was a man-made one. It's best if the storage area is dry of course.
Don't use the same sharpening tools on stainless and non-stainless blades. Many small particles of non-stainless material will be embedded in the stainless and can become the starting points for corrosion.