Hello ErnestoJuan,
Very nicely done! You have 'saved' a piece of history, and I agree with the others, it is indeed gratifying to see a once proudly worn sabre brought out of dusty obscurity. I have tried going through typological references of regulation patterns, but have found nothing that distinctly corresponds. Although regulation patterns, by definition, generally follow easily recognized forms, those manufactured by various contractors often produced variants, especially for auxiliary or ersatz units.
This appears to me to be most likely from mid to latter 19th century, and probably Northern European, which of course seems a given since it was found in Amsterdam. With that I checked through "Blanke Wapens" by J.P.Puype (Amsterdam, 1981) which is focused on the military swords of the Netherlands from c.1600 through the 19th century. As I have noted, nothing with enough similarity. This would not be a French military sabre of the periods discussed as these were typically brass hilted. Your example is of course iron, which appears 'japanned' (painted black to prevent rust).
Also the strap type attachment of the knuckleguard to the capped pommel seems very unusual, and recalls this form of join often seen on colonial weapons such as the Spanish Colonial espada ancha.
Although the sabre seems possibly Prussian by its overall appearance, it very well could be either Swedish, Danish or even a Dutch variant. The strap type pommel attachment seems as if it may correspond to the 'klewangs' used by Dutch navy at end of 19th c. and into WWI period. It may be possible this sabre might date into that period and been issued to cavalry of the time but more research into variants needed.
Possibly best bet at this point might be getting hold of Jean Binck or Richard Dellar over at regulation military swords (SFI) , both of whom are brilliant in identifying these regulation weapons. I just wanted to have a run at it too!!
All the best
Jim