I agree with Sanctaphrax
Mm, you could give the grandsome some titanic bronze armor (I'd suggest not a full one, because that would make him too powerful, but perhaps some parts of the body). Besides that, I think it is interesting to play with auras, like...people become more creative but also more chaotic around him, so you can't have militia but you can have hordes around him. Also, Prometheus is a friend of humans, so why not doing something like his presence makes humans stronger and supernatural beings weaker, thus reducing the differences between mortals and supernatural ones?. Of course, you can make that power as strong as you need, and play with the range of effect according to your needs.