Welcome to the forum Caedo. Just a few observations. The dress does not appear to have been made for this keris as the fit is questionable. You may be right that the blade does not originate from the same place as the dress, though i am not convinced that this is a Javanese blade as Penangsang suggests. The sheath is a nice wood. The fittings look 20th century to me, but you photos aren't too good and your colors appear off. Are the fittings silver or some other metal? The hulu looks like bone to me. I cannot see in your photos tell-tale signs of ivory grain. The mendak seems incorrect for this dress as i believe this is a Javanese mendak and you need a pendodok in it's place.
The materials look to be to have all received some level of an aging process so i suspect the entire ensemble may well be late 20th C. But i hand, or even sharper photos in better light, might reveal otherwise.
