So in my process of learning more of Blender, I decided to try to make a pentagram to replace the cross. I cannot say it was very hard or long to make but I learned a bit more about Blender while doing it and this is what count the most to me.
When I was putting it in place on the dress and adjusting its size, I had to modify the chain to which it is attached. I exported the full necklace to then transfer it to the outfit. Even if it is only a very simple pentagram with very basic textures, I decided to also make a standalone necklace with it. I packed the nif and textures and put it in a small jewelry box in the Arcane University tower hall.
You can get it here: http://www.mediafire.com/?p9mglm6stx6r7bc
If you want the Demiwitch dress with the pentagram, you can download it here: Pentagram_DesuchanDemiwitch.7z Just instal it over Desuchan's Abbotsford.