#1.0 lore

Looking at both profiles, we see the truth of the character start to make some sense.  The real Nael died prior to 1.0 even starting.  The Nael we see throughout 1.0, and again in Coil is his sister, Eula. As there was no voiceover work for the character in 1.0, and due in part to a lack of gendered pronoun use in the Japanese version, there was no way for English localizers to differentiate so they defaulted to referring to Nael as male. And since I don't have access to all of Nael's Japanese translations from 1.0, I can't say for sure if the character was using a male or female pattern of speaking, but I would have to assume, since Eula was disguising herself as her brother, they might have had her using male dialogue to make it more believable. This would also, understandably, cause some confusion when it came down to translation, because to the localizers, a character speaking in the role of a male, with no visible or audible evidence to the contrary, would easily make the assumption that Nael was in fact a male under all that armor.  Unless explicitly told otherwise, they would have had no reason to think Nael was female.

One might think, however, Nael's men or really anyone she spoke to would canonically be able to tell the difference unless Eula was clever enough to find some way to alter her voice.  It's not a far throw to imagine the Garleans might have had voice altering equipment, and that she might have built something into her helm to further solidify her ruse.

*This isn't the first time a character's gender has been lost in translation, either, and it's not just Square Enix that does it.  See also Guilty Gear, where the character Justice was originally referred to as male in the English iteration until a couple of installments later in the series.

Another point of confusion came from Coil in ARR, where the English dialogue between Alisae and Darnus doesn’t help to clarify things at all, and contributes to the theory that the female version is partially constructed using Nael’s memories of Bradamante:

Alisae (English): "Bahamut denied you death, and imprisoned what little was left of you in an aetherial shell resembling... what, I wonder? Images from your memory, perhaps?" Alisae (Japanese): "But for some reason your aether was captured by Bahamut and you were rebirthed in an aetherial body." Darnus (English): "No... A moment... My thoughts are clouded, and this body is not mine own." Darnus (Japanese): "Oh, now I see. Without realizing, I became enthralled... by the ancient primal Bahamut, sealed inside Dalamud." Darnus (English): "As did the frail child I once was..." Darnus (Japanese): "the weak girl I once was."

So as recently as 2.0, we had confirmation in Japanese that Nael was female, but the localizers for whatever reason omitted this detail.

Prior to this, however, I would say the fact that everyone believed Nael was male the entire time is testament to just how deep Eula’s ruse went.  She was so good at covering her tracks, she had everyone fooled into buying her game.  There was no reason until then for even the devs to reveal otherwise because this is exactly what the world was meant to believe.  Eula was, hands down, a genius in her scheme, deceiving not only the players, but an entire Empire.

One thing to note which, as far as I’ve seen, has not been made clear by the devs is Eula/Nael’s lineage.  Some sources claim the Darnus family were descendants of the Allagan Empire, which is why they would have been entrusted with keeping some of their technology, but I don’t recall this being clearly stated in lore.  I’m sure someone out there could confirm this one way or another.  Though her lore book profile says she was heir to her family’s secrets, which were secrets of the Allagan Empire, this doesn’t necessarily state outright that they were of Allagan descent, it only implies that they were entrusted to keep information about Allag. The Lunar Transmitter, housed in Castrum Novum in 1.0, was Allagan in origin, and was used to pull Dalamud back down from the heavens where it was left ages ago.  It was destroyed in the players’ attempt to halt the lesser moon’s arrival, but ultimately this failed to stop it as Nael started using herself as a beacon on Riven Road.

To Kill a Raven - 1.0 Final Boss fight

The final boss fight of 1.0 was, of course, a two-parter.  Nael transforms into Deus Darnus part way through, albeit without the twisted dragon-like form we saw later in Coil.  It was also a lot more challenging than the Coil versions, partly due to some of the mechanics involved, and a less-than-stellar combat system.  Here's the video of the final boss, uploaded by Mike Kierstead on youtube:

(I don’t know why tumblr is screwing up and putting the boss fight video link at the very bottom, but I’m not able to fix it, sorry.)

After Nael was finally defeated in 1.0 and Riven Road crumbled from the sky, so too did the gunhalberd Bradamante plummet to the land below.  And what became of it then...?

Uploaded by moonstar312 on youtube.  The video link starts right where Bradamante is found, but the entire video is a compilation of the 1.0 Hildibrand storyline, and well worth watching.