I have a WW1 1916 DWM luger I was looking to get a correct repro holster for display purposes, they offer dyed brown and natural brown leather, I would presume natural leather would be correct but I'm not sure.
I’d go with the natural. The truth is most 08 holsters made prior to 1919 were in some shade of brown leather ranging from fairly light to darker with a reddish hue. Many were dyed on the front side particularly, during the war but the dye or maybe for some polish (black) did not take well making these now blackish brown. A factory dyed black army holster from WWI would not look correct