Predictions for job(s) in the next expansion?

[CKNovel]

I think my main sticking point is that it seems weird that Zenos (whose trailer appearance is being used as "solid evidence"), a swordsman trained in specific styles of swordplay and with a known proclivity for collecting swords, would suddenly pick up a scythe.

That's probably a "lore" reason. Zenos never liked the gunblade used by Garlemald. He suddenly picked up a katana not because he was a massive weeb, but because he was interested in the blade.
Between gunblade and katana, the later is much closer to a scythe. I'd say Zenos originally was attracted to Scythes, maybe due to past life or something in this idea. That's why he was interested in the katana.