Hi, looking at the blade (including the tang), I feel that it is most likely from Sumbawa. The blade form in general can be found along Sumatra and along the Straits of Malacca and Sumbawa. I've seen example of this form in what seems to be authentic fitting dress. How this piece gets its current fittings, I've no idea, although other members had presented with some nice ones..
What makes me think its probably Sumbawa are.. the indicators from the blade base area, includes the awkward form at the
gandik area, the
sogokan, the
greneng area and the long tang. The blade doesn't fit that well in the sheath. The mouth where the
kembang kacang (belalai gajah) is, needed to be made bigger to accommodate the blade to fit the sheath (post #10).
