If it's real buckskin, I wouldn't put anything on it. Is it smoked? I've got a brain-tan buckskin quiver I made several years ago and it still looks good after being carried around in the woods hunting and shooting, rain, snow, all kinds of nasty weather. With buckskin, the stuff it picks up over the years just adds to it's natural character.
PS-you realize that you can't tell us about it without showing us some pics-we're photo junkies lol.