White Mage isn't listed under the jobs. Probably one of the most important jobs to be listed for this item, too. Although anyone could just look at the picture underneath as I do. <_<
You can get this from trading in 10,000 Assault Points for Leujaoam Sanctum, to Yahsra in Aht Urhgan Whitegate. [L-9/L-10] You need to be level 60 to equip it, as well.