[quote=Kestrel]
Basically you have holders born with their abilities as well as those who obtained them through surgery. Ramza was born with it. Lux for example has artificial holder-ship.
[/quote]

Emily had the pleasure of both, her manna too little to note since all she could do was hear Cerberus's voice. Surgery increased as well as added to her natural manna, creating a minor side effect and turning her into a Rook. Nathair was gifted with strong natural manna as shown by summoning Quartz at an early age or he wouldn't have survived long, lol. :p Point is, it doesn't add anything extra other then appearance in the CS.