Unusual grip solution on a klewang

[VVV]

Here is a probably Sumatran (Jambi?) klewang with, for me at least, a unique feature - a trigger-resembling resting place for the index finger.
It feels very comfortable when using it.
Are there any similar solutions in swords from other regions?
I can't recall that I have seen it in any other swords from the Malay archipelago.

Michael