Current problem with battle materia

[VeyaAkemi]

At least give us the option to upgrade them to a higher tier.

That already sorta exists, but it is hardly reliable, you can give 5 Materia to Mutamix in Central Thanalan, and he will return a random Materia of same color of equal or higher tier if they are all the same color, or a random Gathering/Crafting Materia of same or higher tier if they are different colors, though hardly anyone would consider using this for upgrading Materia since the chance is fairly low, and instead use it to turn useless materia into Crafting/Gathering Materia that is actually decently valuable for how easy it is to get them.

There is even an achievement for getting a tier upgrade from Mutamix, and a special animation the first time it happens.