How do i build Nahida?

I see that people usually recommend sac frags for her but i don't have it. I do have a widsith and mappa mare so i was wondering which is better or maybe there is a craftable that i don't know of? . In any case I need advice on the weapon and also the general build like is em better than crit in general?

Here is my curent build, Feel free to suggest any improvements.

https://preview.redd.it/6urpr1j68ree1.png?width=2107&format=png&auto=webp&s=71f5d101eb285180a008468325a0c8a579d63660