I feel like a job's identity should be able to be described in very simple terms that can be broadly interpreted through mechanics. Whether or not they currently succeed in delivering these identities can be up for discussion.

PLD: knight
WAR: berserker
DRK: self-sacrifice
GNB: recklessness

MNK: body-weapon
DRG: spearhead
NIN: assassin
SAM: discipline
RPR: gluttony

WHM: restoration
SCH: swiss army knife
AST: fate manipulation
SGE: medic

BRD: rock star
MCH: engineer
DNC: cheerleader

BLM: destruction
SMN: summoner
RDM: duality
BLU: magic trick