Congrats, that's a great catch!
From what I understand at the moment and am able to see, the blade could be earlier then 1800, the dress perhaps before 1850.
D'accord. As you mention, the edge seems to have seen some revision; still it looks like the blade was slender to begin with...
What about the inlay? Any translations forthcoming? (Close-ups would certainly help.)
The hilt really seems to be one of those one-offs that clearly exhibit Chinese taste and probably got commissioned for wear by a Peranakan (which doesn't help in placing the ensemble since this could be just about any trading port throughout the archipelago as already mentioned).
IMVHO, the scabbard seems to be the best bet in placing the ensemble.