Thank you all for your comments!
Willem, thank you for the hint in direction Kutai.
And yes Charles, one side seems to have once a reinforcing of some sort.
The scabbard is in bad condition, only the front from ebony (?), a very hard wood is nearly undamaged. Only the now too wide upper rotan binding holds the parts together. But you can see where the from Willem mentioned further fine rotan bindings once where situated. The remaining binding at the handle is very brittle.
The blade is well used, several edge nicks are visible, the overall patination shows great use and age.
Attached are some improved pictures.