Citing from "Arms and Armor from Iran," page 201, column 1, e
"The double-edged, straight swords with downward quillons were by no means a revival movement specific to the Qajar period. There are a number of Iranian straight swords from earlier periods kept in Russian museums as discussed earlier. Hence, the tradition of making double-edged, straight swords in Iran goes back to the Timurid and Safavid eras, meaning there was a coexistence of straight and curved swords during the Safavid era [...]"
Further down the lines Mr. Moshtagh discusses briefly the Qajar straight swords stating that even some with highly decorated blades were fully functional.
So it seems I was wrong twice
1. saying these swords are not mentioned in the book, and
2. in my previous assumption, as I underestimated the qualities of the decorated Qajar "revival" swords.