i have no problem with exaggeration, thats all good and proper. the redguards portrayed in that book are nothing like the redguards of today; they don't share the same values, have the same basic language, etc. if i had to take that book at an in-universe face value position, i'd say it was written by an imperial living someplace in leyawiin who has never seen any redguards.
Forgive me if I misunderstand, but I'm not sure I see the contradiction. As I said, I'm new to the lore, but as I see it Torn's Sword Hunt had created a warrior elite of relatively few sword singers compared to the vast majority of Redguard commoners who were not warriors at all. The highest aspiration they could hope for was artisan. All that these commoners knew of history was 300+ years of civil war leading to the assassination of Sesnit. After that they got more civil war that made the previous wars 'pale in comparison'. By the end of the seventh battle of the 'War of the Singers' I don't think it's unreasonable to assume that the average commoner would have seen the sword singers as 'red with blood', virtuous or not.