The spot is glue. They apply glue to the welt and stitched area of the belt loop. The maker of the sheath simply dropped some glue on that area. I use sno-seal on my sheaths.
That’s why I like building my own leather sheaths I always finish the inside treated like I own it and it’s for me. I just ordered six new Lion steel knives beautiful sheaths …. they have not been finished properly inside or out the edges on the trims not burnished the leather was dry and I dropped some water on to see if it had a finishing coat and of course it had not so away I go four more hours To finish the sheaths properly ,…that being said there’s still one of the nicer sheaths that come with a knife
Looks like it works. I just read ad article that Ballistol Maintenance oil works well too. It will soak into the leather and prevent the knife from rusting.
Leather treatment should be used every few months. Anything with grease will cause leather to rot. Tanning the leather is taking all moister/ grease out by drying basically. Leather treatment for saddles is probably best.
