Holy Knight and Paladin are interchangeable in FF games. In fact, in later FFT games( FFTA), they renamed Holy Knight back into Paladin again. There was no concept of Tanking in FFT, so they made Holy Knight into a DPS. They removed the religious aspect of Paladin in FFXIV because it's an MMO and they didn't want to anchor your character to having fealty to any deity.


Also Requiescat is a nod to Lightning Stab/Hollowed Bolt.