Well since everyone is giving good/bad ideas for ffxi might as well jump on the bandwagon...
(Guess which ones are awful! :D)
WAR:
-Give them a job ability that allows them to change their weapon type (ex. Piercing Edge, Blunt Edge, Slashing Edge)
MNK:
-Create a new weapon type "Tonfa" that increases Evasion and Guarding Skills (equip able to PUP also)
THF:
-Give them "tools" that they can only use in battle.
RDM:
-Give them a Job Ability that allows them to store a "almost fully casted" spell. They use the job ability again and the spell is casted.
BLM:
-While under the affect of the job ability "Manafont", they will get access to "forbiden" spells.
BRD:
-Allow them to have a 3rd song up that is purely defensive such as carols and warding songs.
-Allow them to have access the weapon skills "Vorpal Blade" and "Dancing Edge" natively.
-Give them a job abilty that allows them to instant cast etude's on themselves only. However the effect of the etude won't last very long.
PUP
-"Conserve MP" attachment should change the behavior of automaton spell casting based on how many dark maneuver are up. They cast nukes less frequently (RDM/BLM) and use regen/enfeeble/d.o.t. spells more frequently (WHM/RDM).
-Create a "Adds Enhancing Magic" attachment that allows automaton to have access to enhancing spells. Spells are exclusive to frame types.
-Give automatons a "job ability" that they can use (Valdorege has one).
-Add a BRD automaton that sings songs based on active maneuvers. More maneuvers stronger or mixed effects.
DNC:
-Give them "dagger mastery job trait" that increases dmg done and lowers the amount of tp enemies gain from it.