To Unlock Ixal:
Quest: A Bad Bladder (technically requires level 1, but see prerequisites)
Location: New Gridania (X:9 Y:11)
NOTE: You'll need a crafting job unlocked (of any level) in addition to your 41+ combat job to actually do any Ixal quests past this one.
Thanks to twitch.tv/Zephyr for making this guide possible!