Hi Chevalier,
I can't speak from personal experience here, as all the earliest Kaskara's I've seen or owned had trade blades or what seemed to my eye to be copies of trade blades.
however, I do think that the 'crusader' influenced theory is more than a little based on the cruciform hilt which is so iconic in European medieval swords.
It seems just as likely that the european origin theory is slanted from our cultural viewpoint, and the trade blades were made specifically to accomodate the local preferences rather than being sought out just due to an admiration of earlier european swords.
Certainly the 'crusader' influence is a popular view, but so also is your theory.
Look near the bottom of this document:
http://www.daviddfriedman.com/Mediev...rticles_IV.pdf