What Job would use...

[Alacran]

Why not Dancer? It's movements would certainly be fluid enough.
https://www.youtube.com/watch?v=faQO57Iwlo0

[Zukissa]

"spellblade" type character. Melee / Magic hybrid.

[Musashidon]

a limited one.

[hynaku]

Maybe a freelancer class. Didn't they use double blade staff. Also think mime uses the same weapon to.

[Reynhart]

Judges

Judge Magisters wield paired weapons, one short, and one long; separate, these weapons act like single-handed weapons, conjoined, they act akin to a double-ended polearm, with both blades' edges facing outwards rather than a cyclical parallel. One example is of Judge Gabranth, whose weaponry comprises of the Chaos Blade and the Highway Star.

Source

It have to be a tank right
:^)

Cloud = ff7 = Dark knight
Squall = ff8 = Gun breaker
Zidane = ff9 = ????

In a twist, yes, it could be a tank

[RitsukoSonoda]

Fighter?

Although 8-bit theatre would have me rather fighter use swordchucks.

[Ramesses]

To be honest, I used to joke in the past that the winged Judge from FFXII Revenant Wings (see image below) should have had a double edged weapon like Gabranth's.

[Kreyd]

How about Runefencer/Runeknight?

It's a medium often requested job and people often start argueing about longswords beeing to similar to DRK's greatswords.

[Seraphor]

How about Runefencer/Runeknight?

It's a medium often requested job and people often start argueing about longswords beeing to similar to DRK's greatswords.

I'd be on board with that.
Zidane did have his magic attacks via Dyne after all.

[Jonnycbad]

FFXIV's DRK is a fusion of Rune Fencer and Dark Knight, just as Warrior is a fusion of Viking/Berserker/Warrior jobs. Rune Fencer specialized in great-swords and mitigating magic damage, which is a theme that DRK specialized in 3.0 (and less so in 4.0 due to the homogenization of tanks, but still there). Moreover, activating Blood Weapon creates red runes on your blade for a few moments during activation.

Also, Zidane used Dyne spells during trance, which awakens his true powers as a Genome from Terra. All his Dyne spells utilize Terran runes and script, and were abilities imbued in him at birth that he forgot about and only realized when he's under huge emotional stress.

That said, the swallow, or eku, is a weapon that originated from Okinawa and resemble and oar. They were only used for self defense but were basically double-sided naginata. I could see them being a weapon for a class that specializes in Staff/Pole in general. Kind of like Raijin in FF8 or any of the melee staves used in FFXI.