So, awhile back I made a thread pertaining to Garlean naming conventions. The original can be found here. I decided to revitalize it, as we ended up eventually getting this reply from Fernehalwes:

Quote Originally Posted by Fernehalwes
No time for a WMD, so this firecracker will have to suffice until the loremaster and I can put together a complete post.

FUN FACT: The 'middle names' of the Garelans who have appeared in XIV represent their relative position within the Empire's sociopolitical structure (including the Imperial Army).

BREAK!
Seeing as ARR is finally out, I was hoping we might finally get the update we've been waiting so very long for. We've learned a lot since the game has released, but we're still lacking confirmation on so many things related to the Garleans, their language, and their naming conventions. This recent post by Mtoto Wamoto seems to hit the nail on the head with a lot of what we've learn from ARR's storyline.

Quote Originally Posted by Mtoto Wamoto
Actually, I have a bit of info considering we just recently got some new names to the list.

Nero Tol Scaeva - Nero is likely just a direct rip from Latin, which means powerful, strong, vigorous. Tol is likely the naming title for his rank as Tribunus Laticlavius. In the Roman army, the tribunus laticlavius stands directly below the legatus and above the other five tribune known as the tribuni angusticlavii. His last name could be related to the genus of hover flies of the same name...hover as in, "Let me hover over this cliff and spy on you."

Livia Sas Junius - Livia is probably a reference to the wife of Augustus, first emperor of Rome. The name means olive in Latin. Sas is likely reference to her rank of Tribuni Angusticlavii. Junius could be either lunius or junius, both meaning June. It could also be reference to Juno, the Roman goddess of marriage and queen of gods.

Rhitahtyn Sas Arvina - Because he isn't of Garlean blood and is from a subjugated land, he doesn't receive the typical Latin name. Instead, he is given a traditional Roegadyn name. Rhit in ancient Roegadyn translates to Right, and Ahtyn translates to Judge. His first name literally translates to Right Judge. Sas is likely reference to his rank as Praefectus Castrorum, which if we go by Roman ranking, is pretty much the same rank as tribuni angusticlavii, both being the third most seat in a legion following the Legatus and the Tribunus Laticlavius. His last name, Arvina, may actually be Latin. Arvina is defined as meaning fat, perhaps in reference to his size. Coincidentally, Gaius Papirius Carbo, a Roman tribune in 90 BC, was known for the law which he carried and was surnamed Arvina. Law...Judge...Arvina...Hey...something smells fishy here, Ferne!

So, here's my personal updated list of Garlean 'middle names'.

Military
Van - Legatus
Tol - Tribunus Laticlavius (Second in command)
Sas - Tribuni Angusticlavii, Praefectus Castrorum (Third in command)

Royal Court
Zos - Emperor

Scientist/Engineers
Nan - Engineer

Also slighty off topic, but if I had to bet...I'd wager to say that the whole Color Animal title that Gaius and Nael have aren't exclusive to those who hold the rank of Legatus.

Nero's helm appears to be that of a dragon, or even a drake. I wouldn't be surprised if his other title is the Red Dragon, Crimson Drake, or something along those lines.

Livia's is interesting because her helm is rather....oddly shaped. Since her weapons are actually mounted to her, maybe they play in the design and the source of her name. I don't want to put a whole lot of faith behind it, but perhaps its another bird reference. But then we'd have two white color and bird names. Not sure the power rangers would approve. Perhaps instead of white, her title uses Ivory, or Alabaster, both very precious and valuable materials. It could match up since her weapons are named Aglea, which is Greek for splendor, brilliant, and shining one. As for her animal name...I've no idea. Maybe she's a turtle. THE ALABASTER TURTLE.

Rhitahtyn seems somewhat obvious to me, but I'm ready to be wrong. My guess is that he goes by the Black Bull, if not the Onyx Bull or some other synonym of black. His weapons, Tartarus, is likely a reference to the Greek mythos of the same name which is the infernal regions where the wicked are punished. In Roman mythology, Tartarus is the place where sinners are sent. His weapon names seem fitting for judgement, living up to his translated name as the Right Judge. Maybe he is the Onyx Bull of Judgement. Who knows.