Hello All,
Maker of the knife sheath here.
I can tell you with 100% accuracy, the knife worn by Pratt was made by Steve Auvenshine. I received the original knife FROM HIM to make the custom scout sheath for it, and it is the exact same knife that is in the movie that Chriss Pratt is wearing S.O.B.
Steve is a very low-volume blacksmith. He supplied a total of four identical knives for the movie. One remained in the sheath through the whole of principal photography. One was used as a working knife whenever a shot required prying/cutting/etc. The other two were worn by the stunt doubles.
I know this because I provided the sheaths for all four copies.
Steve doesn't have a website, so if you are interested in one of his knives, you need to drop him an e-mail or call him. Send me a PM and I'll pass along his contact information.