The best I can tell is that there was nothing, no writing or printing, blotted out. The holster has apparently been in the same family since the 19th century. I've wondered whether the holster and a gun? may have been confiscated by some authority and held for some time, then returned to the owner. Maybe the blue bars are the markings indicating that. This is pure speculation. I know of no example of such a thing happening.
I would guess the holster was for a revolver (possibly 22 lr) or a long barreled semiauto like a colt woodsman or the like. If you have such a revolver or pistol put it in the holster and see how the lines line up with the grip.