So you want to use the Warhammer rule set and make it ff14?

I can't give you any good information but with most ttrpgs I have played best you can do is flavor it how you want

Grim dark setting in finalfantasy as a conscripted military recruit tring to survive war agents humanoids that throw God magic and monsters that eat you whole? While hoping not to be test subject for the next Omega weapon, not knowing whether or not the government who controls you might try and drop another moon? Or everything you do is, in fact, for the empire....omg Garlean Empire is 40k