Just tossing these out:

Class: Gunblade
Role: multi-role
Strengths: multi-range combat class, multi-hit melee ws, decent magic skill, highly accurate
Weaknesses: cannot wear heavy armor
Job: Red Mage

Class: Mercenary (Greatsword)
Role: DD
Strengths: specialized in breaking enemy defenses, quick combos, can function as a parry tank
Weaknesses: less dmg than mrd, tanking skills are not as high as gld
Job 1: Samurai (gains ability to use exclusive Great katanas, can easily chain combos)
Job 2: Dark Knight