Hi Rick,
I very much agree that this is probably an English backsword blade that may date back to late 17th century. The patination and deteriorated stamp in the blade seem to correspond to blades of that period I have seen. Actually I have seen a very similar stamp in about the same condition on a Cromwellian period blade.It is not at all unusual that these swords often carried straight European blades, especially English. Anthony North in his "Islamic Arms" (Victoria& Albert, 1985, p.28) notes in caption of illustration of portrait of an English officer c.1617 , "...the captain of a Trained Band is shown wearing a typical Moroccan sword and holding a staff of office. These swords with thier distinctive hilts seem to have been fashionable in the 17th century in England, as they are shown in portraits of the period".
It would seem that while these swords had a degree of popularity in England in those times, at the same time the English blades had similar popularity with the Moroccans in thier sa'ifs (nimchas). I have found English backsword blades of even latter 18th century mounted in Moroccan swords with variant shellguard hilts, so this seems a long standing practice. With the position of the stamp on your blade and the distinct back fuller I would suspect this blade is probably end of 17th to early 18th century by its appearance.
While the blade seems quite old as noted, the mounts seem of course much more recent, which is not at all unusual as it is well established that most swords of these forms were often refurbished over many working lives.
Nice example with a outstanding blade!!
Best regards,
Jim