Most braided slings have whipping where the cords meet the cradle.  I suspect that this is a means of securing the ends of a line used to weave the cradle.  Binding the cords with series of half hitches or some other way produces rigidity and maybe bumps both of which I think are detrimental.

On the sling that I have been working on making (I made some models to test production viability) I braid the release cord around core strands and when the right length is reached I use the core strands to weave the cradle and then they go back to being core strands in the retention cord.