Thank you Oliver!
I well recall that article on the Assad Allah pictogram on the Persian trade blades, which was brilliant and a most important reference in the study of these notable blades.
As noted, these kinds of symbolic devices became well known as seen on many North African swords, especially it seems on kaskara as these swords became most important in status and religious affirmation in Sudan and Darfur in the latter 19th century.
The toughra in this case, rather than being a traditionally appointed device is more of a trope signifying power and authority as noted. The use of other important symbols or markings also use that convention, for example the familiar cross and orb mark from German blades was often seen as a drum and sticks, an important symbol of a chief or tribal leader often copied onto Sudanese blades.
Clearly the importance observed toward these kinds of marks whether Ottoman or European alluded to power and essentially imbued magic into the blade of the sword.
Such symbolism would not require literacy as a symbol is a subjectively understood device which would be recognized to the initiated accordingly, as you have pointed out.
Thank you again very much for responding on this!! and its great talking with you again, its been a minute
