The 'mickey mouse' hilt form, spans quite a large geographical region in Sumatra. There are examples on Palembang, Minang and many other pieces.
Adni's classification of hilt forms had identified the hilt as Minangkbau, (based on Malay Art Gallery archives.)
Michael (VVV) have examples of this hilt form on various types of Sumatran keris.
On a Minangkabau's keris:
http://www.kampungnet.com.sg/modules...view_album.php
On a Palembang keris:
http://www.kampungnet.com.sg/modules...view_album.php
In Van Duuren's, The Kris, Page 54, there is a similar form which mentioned it as from South Sumatra.
In Kerner's, Keris-Griffe - Aus Dem Malayischen Archipel, Page 52, Fig: 40, another 'mickey mouse' but only indicated as from Sumatra.
As for whatever left of the sheath, and the blade, it seems Central Sumatra to me.
"Ganja Iras" is a purpose-built piece. Where it was believed, with proper ritual, could be used to penetrate an 'invincible' warrior, (those that practices a kind of mystical 'warrior-magic').
Others have stated before that it is a short-cut, cost saving means... etc. However, in the Malay mystic world, it hold certain values.
