It has always bugged me that upon changing jobs, core bits of jobs which I've shown mastery over get lost in the change. I started as RDM, and when changing to another mage at 75, I felt like I was casting in slow motion. After leveling MNK, I would have to do something on WAR, and my weapon would be stripped, oh... but I seem to have temporarily forgotten how to punch? NIN, THF, DNC all dual wield well, then I decide to play around on BST/WHM, and... no more dual wield.
My proposal is to allow someone to permanently purchase job traits with job points, which they have already unlocked on a job. For example, once you hit level 99 Ninja, and unlock job points, spending 5 job points to unlock the job trait Dual Wield on other jobs. These job traits could be only available to other level 99 jobs, or they could become available at the levels at which the original job unlocked the job trait, (ie: Dual Wield rank1: nin10, rank2: nin25, rank3: nin45, rank4: nin65, rank5: nin85)
rank1 = 5 job points
rank2 = 10 job points (15 total)
rank3 = 15 job points (30 total)
rank4 = 20 job points (50 total)
rank5 = 25 job points (75 total)
war: attack bonus, defense bonus, double attack
mnk: martial arts, subtle blow, hp bonus
whm: cure potency, magic defense bonus, tranquil heart
blm: magic attack bonus, magic burst bonus, conserve MP
rdm: fast cast, magic accuracy, shield mastery
thf: triple attack, crit damage bonus, skillchain bonus
pld: defense bonus, shield mastery, crit defense bonus
drk: attack bonus, occult acumen
bst: killer effects, stout servant(pet:-dt)
brd: magic accuracy, fencer
rng: accuracy bonus, rapid shot, recycle
sam: store tp, skillchain bonus, zanshin
nin: dual wield, subtle blow
drg: pet:att/mab/ratt, conserve tp, accuracy bonus
smn: auto refresh, pet:att/mab/ratt, pet:acc/macc/racc
blu: um...
cor: rapid shot, recycle
pup: pet:att/mab/ratt, pet:acc/macc/racc, Stout Servant(pet:-dt)
dnc: dual wield, crit damage bonus, conserve tp
sch: conserve MP, magic accuracy, occult acumen
geo: cardinal chant,
run: magic defense bonus, tactical parry, tenacity (resistance against all status ailments)
by no means a final list, resist traits and killer traits are noteworthy possible additions to the list. Please share your thoughts for improvements and changes to make this more realistic and feasable.