Hi Taylor. Basically the scabbard is hardened by heat treating. I don't harden sword scabbards as much as some knife sheaths. Just enough for some rigidity. For most hardening, the leather is dampened as you would prepare it for carving, then baked at from 130° to 140°, until completely dry. At these temps there is no damage to the molecular structure of the leather. Chuck Burrows can better explain exactly what this does internally, but the result makes vege-tan much like dry raw hide. Hard and springy. This method is a dry version of "cuir bouilli", or boiled leather, only much safer for good results. I have found, with some practice, that it can be done useing a heat gun, but there is a risk of over heating and wrinkling the surface if not used very carefully.
