I like this idea but also agree with Seriha for not calling it Faith.

For those who know, Faith/Magick and Bravery/Valor were staple buff spells in previous FF's augmenting Magical and Physical power respectively. They were so good that I could easily run a full party of RDM's in several FF games and succeed.

I genuinely wouldn't mind RDM getting Faith and Bravery. Or the OP's idea.