I've been using Aquasesl for many years to repair dings and abrasion areas on Neo. skirts. It's always held up well. I use it on my Gortex Drysuit and top too.

Neoprene cement is meant for the bonding of neoprene, but not the nylon or Lycra skin. It's actually a thick solvent. (I used to repair dive suits too) It dissolves the mating pieces of neoprene so you can push them together and the softened neoprene sticks to the other pre-softened piece actually fusing them. Technically you would glue pieces together and top stitch the seam too. Then I would coat the seam with Aquaseal which would bond well with the nylon outside layer.

I think the guy posting just wants to seal the stitching of a skirt he's making in which case Aquasal would be perfect or any tent seam sealer.