Hello Franc,
Thanks for the additional pics!
They confirm our earlier thoughts: Blade, horn hilt, and scabbard are genuine and also exhibit the expected wear of a 19th c. piece; I still believe the light streaks at the pommel to be much later additions. Aceh blades like this sikin panjang or peudeueng pajang are known to be usually very well forged and of high quality - an etch will tell a bit more but is not mandatory at all. The scabbard is of above-average quality and almost certain to originate from Aceh proper; try to look for inscriptions while carefully nourishing and cleaning the wood. More on the calyx later.
It isn't a bad piece - let me repeat: This certainly is an interesting grab!
Let me know if you ever get tired of it...
Regards,
Kai