All i can say wihout risking being contradicted is that this is a very nice sword.
Portuguese ... i don't know. Spanish ... maybe
. This frequent doubt is the reason why experts, certainly the wiser ones, like to call them all Iberian, unless
some evident detail allows them to be more specific. Swords, like cannons, appear to have a higher value when mentioned by sellers to be Portuguese. I take it for me that this is due, not to quality factors but, statistic ones. Portugal being a smaller country and having had its armament capacities shrunk during history for reasons known by historians, makes antique weapons be more rare, thus more valuable.
Your beautiful example has all the ingredients of a sail guard sword;i have a problem in mentioning the so popular "rapier" term, until i know the with of the blades; at least that will 'partly' legitimize the rapier attribution in its non peaceful conception.
The Portuguese call this type "guarda de vela", the Spaniards "guarda de barquilla"; one means sail, the other a derivation of boat, so both appointing to the same.
A certain author cites the different reasons for their appearance, one being the reflex of our passion for the sea, which makes them typicaly Portuguese (?) and the other the transition from the heavy complex hilts from the 1600's to a phase of more 'allégé' swords, both military and civilan. You see them with plenty variations; those with more agressive blades, those with hilts well worked up and those well refined with gold plated hilts for the wealthy officers. Concerning the blade, i would recall an intersting note; Portuguese did not forge blades, at least in massive production terms. In the several cases we find inscriptions in them, those are more patriotic quotations (certainly localy engraved) than actual smiths marks; so you could say that a certain sword blade is Portuguese because it belonged to a Portuguese but not that it is Portuguese made.
I have a sail guard sword from the XVII century, that i assume is Portuguese only due to the context in which it was acquired and the blade, as so often happens, is a Solingen product, forged by PEDRO (PETER) TESCHEN.
I am sorry for being so boring; don't fall asleep when you read all the above wanderings... which are not expertly guarantee; be carefull