Lessee....
we have
Alpha
Beta
Gamma
Sigma
Omega
Zeta
and Ultima, correct?

Alpha and Beta are Titus and Celestia, a Knight and Sorceress.

Gamma is Dante, a Dragoon. He gives Trey's brotherstone, the Bloodstone, which powers up the Astra Lance to Saturn's Spear.

Sigma is Yin and Yang. They are Twin magi, Black and White respectively. They teach Jez Halley's, the ultimate Time magic.

Omega is Kazuya. He gives Cara the Death's Guise, a powerful armor.

Zeta is Tristan. He gives Erin her brotherstone, Jade. It powers up the Faerie Dart to the Nightmare Bane.

Finally Ultima is Mercy. She will bless the Ultima weapon, and teach Dax the ultimate sword technique "Rapture," which works much like Omnislash.

Like? Dislike? Discrepancies?