Anyone who hasn't already figured this out... this is Doublet-type armor. With some special exceptions (Cerise/Nimbus/Noct/Evoker's/Summoner's Doublets), all Doublet-type armors are usable by the same set of jobs.
If you don't believe me, check the jobs that can use Doublet, Cotton Doublet, Great Doublet, Earth Doublet, etc. etc.