https://en.wikipedia.org/wiki/Children_of_Bodom
Thought follow the reaper was a half decent pull from the page. Other themes continue with death. Given the grim reaper picture twice now it does feel follow the white rabbit like.
Reaper job would also fit for something dark theme'd without making someone question if it's okay to be. Job focused on cleansing the soul, which also happens to have to deal with Anima being in the same expansion. Anima relating to the soul (the name). And soul magic was relatively big part of the last expansion (ShB).
I'm still going with money on something relating to reaper (and potentially Ranjit). And if the name Reaper isn't apt enough for the series, like I mentioned in the other post Ranjit was based off a character from another FF game that was a ravager and Golbez. Golbez wearing heavy armor, a character who used a lot of magic (some dark theme'd), the job supposedly going to be wearing Dragoon armor if we take Yoshida's sort of aside comment on the matter.
Ravager in other FF games often focusing on what our current Black Mage focuses on. So that doesn't help too much in theme, thoughts though. However, ravager does also then fit into the filth and fury of the first shirt's concept.
So double reaper of filth and fury, a reaper (soul / dark magic) theme'd melee job that wears heavy-ish armor? Maybe..