Forbidden Materia

[Holyomen]

Huh? If you add just one materia, then there isn't any failure. It's 100% guaranteed you won't lose the materia and gear if you add just one materia to your item. But if you try to add two, three, or four on top of that one, then there is risk of losing that gear and previously added materia.

EDIT: Ah I see what you're saying now, I think there isn't a "better" reward per se, I think maybe if you have three materia on one item, then maybe you get a bonus but if you're going for that bonus then there's a risk of losing everything you have.

I am referring to forbidden materia, of which we don't know anything about as of yet, not the adding of up to 5 normal materia.
All we know is that is it great power at a great cost.