Playing mostly Healer, I just realized those classes don't really favor one hand over the other too much. CNJ/WHM spells have the weapon float in front of you as you use both hands to cast. AST is similar where you hold the Planesphere in your left hand, draw/use cards with the right, and cast most spells by raising both above your head. SCH has the most favoring with the book in your right hand, quill in your left to write the formulas.
That said, my characters all tend to favor their right hand heavily, as it's what I know best.
That said, my characters all tend to favor their right hand heavily, as it's what I know best.