Ares Phantacites??

So....what are those for? I cannot figure out for the life of me where to use those

Some stones obtained aren't redeemable in the stone exchange NPC yet for their appropriate gear/etc. They do however work on general stone exchanges, though I wouldn't recommend that. I'm guessing when Tokyo/LA and mission tickets come out, we'll have them.

Ahhh okay that makes sense.

Those Ares stones were actually used to obtain the original 13* series, the Ares series. Seeing as Old Type Weapons are no longer in the game, unless they make some modifications in Zig's item trade system, they will likely not serve that function in the NA version since the New Type version of Ares weapons are 14*, but they still do serve the purpose of being an upgrade item for the Austere unit series.