So would the have access to nine skills on top of the six they can already access, or just nine total? Could the five attempts of a magic spell, or ability be in one sparring match or should they only be allowed to try it once? Could we have an NPC who has already "mastered" the job be teaching us the ability to shorten the amount of attempts by one perhaps?

Couldn't do Captain because of the Pirate --> Captain jobs. Unless it's specified as Pirate Captain and Knight Captain.

There is also the possibility of only going up one more class, because most jobs end at about 4-6, and the High Knight is the 4th in the chain. It could just end with Sword Saint, or Commandant, or Knight Captain.