Yes, the tanning of the leather and the finish do matter. Chrome tanned is the worst on knives. Vegetable tanned can be ok, especially if the blade is stainless. In this regard, a lot depends on the blade and the blade’s finish, as well. For instance, I made a small leather sheath from vegetable tanned leather for my Case Winkler Skinner in 80CrV2, which is a high-carbon steel knife with a cold Caswell finish. If I store the knife in the leather sheath and it’s not well coated with silicon, I’ll see some corrosion after a while. So when I’m not wearing it, I leave it out of the sheath on a high shelf.