CON= Wizard (BLM), Priest (WHM), Oracle (RDM)
THM= Time Mage, Dark Knight, Paladin

Wizard (WIZ or WZD)
Focuses on elemental damaging spells and enfeebling spells. Weaponskills enfeeble the target.
Priest (PRS or PST)
Focuses on healing spells and enhancing spells. Weaponskills heal HP, MP, and status.
Oracle (ORC or OCL)
Combines elemental spells with enfeebling and enhancing, such as a fire damage spell that temporarily increases STR of user, or a fire damage spell that decreases the target's INT. Due to their magic focus, no weaponskills for Oracle.
Time Mage (TIM or TMG) lol Tim
Enchancing and enfeebling spells that all relate to time. Physical abilities relate to the same, but not much for weapon skills.
Paladin (PLD)
Heavy light elemental abilities and spells.
Dark Knight (DRK)
Heavy dark elemental abilities and spells.