We've all been synced down below lvl 30 and know how weak certain classes can feel. Tanks don't have their tank stances, dps don't have certain abilities. This could all be fixed by placing abilities on the job stone that you always have available when it's equipped.

This would also encourage people to actually equip their job stones at level 30.

This would give:

PLD - Shield Oath
WAR - Defiance
DRK - Grit
WHM - Pressence of Mind
SCH - Adloquium
AST - Diurnal Sect
BLM - Convert
SMN - Summon 3
RDM - Verstone
BRD - Mage's Ballad
MCH - Hot Shot (or Rapid Fire)
SAM - Gekko
MNK - Rockbreaker
DRG - Jump
NIN - Ninjutsu (Ten)