I agree with the observations expessed suggesting this is quite likely Portuguese and probably end of the 17th century blade. As Rick mentioned, the Portuguese had trade dealings and stations into these regions from many years earlier, and blades often followed these routes. In the book "Homens Espades e' Tomates" (a curious title but excellent book in Portuguese) by the prominant collector Rainer Daehnhardt, Lisbon, 1973, on p.31 a Portuguese cuphilt c.1640-1668 is shown. While the blade is undulating it appears the full length of the blade.
Apparantly these undulating, flamboyant blades had a degree of popularity in Spain (an 18th c. cuphilt, Spanish w.German blade, undulation full length, shown in "European and American Arms" Claude Blair, fig. 136). This fashion carried into European smallswords (Nuemann, 206S, "Swords and Blades of the American Revolution") where an example has again, full length undulation, and it notes "primarily for decoration" which suggests no particular practical advantage intended with the undulations. Such feature was even carried to English officers broadsword c.1775 (Neumann #148S).
The apparant age, fullering, piercings seem to indicate the 17th c. period quite plausible on this blade, with the undulations intended to apply more to Christian symbolism than to practical purpose. In Masonic lore the wavy or serpentine blade recalls the flaming sword guarding the gates of paradise ("Material Culture of the American Freemasons" John Hamilton, 1994, p.149) and though described for American application, possibly the symbolism may extend to the well established military orders in Portugal.
Just some references and observations to support what you guys have already well figured out!!!
Pretty interesting blade that may well have some fascinating history.
All the best,
Jim