I rather agree with Colin. I have a couple of these and whether they are based on talismanic swords is debatable, but I doubt that any self-respecting Sudanese warrior or leader would wave one of these around and have the blade fly out of the hilt (which would certainly be the result). So I'm not convinced that these are even for local use as ranks or emblems - rather I think they were produced for sale.
Yes, for sure there are examples of worthy weapons with thuluth, but they are few and far between. These others appear to be more or less mass produced and follow the same pattern based on etched flat sheet steel, no fixing of the blade to the hilt (its just pushed in and padded), and usually brass non-functional or very thin iron guards. All topped off with a crocodile hilt, often with legs. The small bone handled daggers, and triple dagger sets being equally non-functional and from the same steel, also sporting crocodile clothes.
As objects of study, and interest they are actually quite nice
but not to be confused with functional kaskara.