Hi Kai, thanks for the update.. forgot to check Karsten's "Kris Disk"..

Better pictures of the 1st posted piece are found there, but still no blade visible except for those which are sewar-like, (3 examples).
Hi Michael, nice examples of Si Euli. My obsevations are, Si Euli is typically a sewar-like blade with a sewar-like sheath.. however, the example posted in post #1, probably have a sewar-like blade with a keris-like sheath..
If we look at other weaponry of Nias, we mostly see variation of balato, sewar and badik-like knives, spears, etc.. The same post #1 piece can also be found in Feldman's book "Nias, Tribal Treasures. Cosmic Reflections in Stone, Wood and Gold", again without the blade visible..
The one found in Jensen's 'Kris Disk', Fig 209: "A Chief from North Nias with a Gayo/Aceh type of kris", may be an imported keris used, not part of the local culture. My opinion is, there is no keris culture in Nias.. if there is keris found there, it's most probably imported from mainland Sumatra. Currently I do not have supportive evidence to prove that, but I've yet to see evidence that one does exist to sway my opinion. What do you think?