Based on dress alone i would say this is a Madura keris, not Sumatra. This style of dress is often associated with "tourist" variety Madura keris. Yours seems an older example with an even older blade.
Back in the early 20th century many dutch soldiers brought keris like these back from being stationed in Indonesia. Perhaps one might say that was the beginning of the "tourist" keris. Those bring-backs usually had real, though lower end blades in some sort of carved sheath like yours. Sometimes the figure depicted is a lion. Yours appears to be some sort of bird. You may, therefore, be able to consider this a "tourist" keris, though certainly not in the same way as a contemporary blade in brand new dress made for the market these days. Personally i find keris like this one very interesting and collectable even if there intention in their current form was for sale to returning dutch soldiers. They are a piece of history if you will.
