I'm just starting to play around with Materia, but I've found that Grade 1 is for gear level 1 and up, while grade 2 is for gear level 31 and up, and that grade 3 and 4 are both for level 41 and up.

While I know that the stats might make a difference, I just was wondering why we can't move grade II to 21 and up, keep grade 3 at 31+ and have grade 4 stay at level 41+.

It's just a thought,