I have been playing Persona Q very heavily and started watching a playthrough of P4 Arena Ultimax. The story of Labrys revealed a lot of backstory that I had never seen before.
Now on to my speculations. Aigis, Metis and Labrys have all been given the mannerisms and personality of an anonymous girl. What we know of her is that she was very ill, never able to leave the hospital. She wanted so badly to be a student at the nearby school but never could because of her illness. Rei was introduced in Pq of course, which takes place in a time that combined 2009 and 2011. Labrys claims to have been born in 1999 and being the oldest sister of Aigis by only a few months, we can assume that the original generation of Anti-Shadow Weapons were created a few years before her. Labrys is a gen5 while Aigis is a gen7. The clock tower that is mentioned in PQ was torn down 12 years prior to P4, if I remember correctly, which means it was taken down in 1999. This is not directly related to my statement, but it fits within the timeframe. Rei will have had died before the clock tower was taken down, which lead into the beginning of PQ. If she was at least alive 5 years before the tower came down, she could have been the inspiration for the gen1 Anti-Shadow Weapons. And as far as I know, the sisters never meet the girl, except in visions that they received from previous generations of Anti-Shadow Weapons when they transferred their memories. That means she definitely died before P3.
Now if time 'bears'...Mmheheh... repeating, then labrys living out the dreams and wishes of Rei created the same school all over again, became a student all over again and welcomed both P3 and P4 parties into it....again.
There are of course some holes in this idea, such as the fact that Labrys inherited the Brooklyn accent from her 'mother' and Rei does not have an accent like that. Could it just be an oversight? Maybe she lost the accent during the time she spent with the imaginary students in PQ. If she was only 10 or 10 years old when she died, then she could easily have acquired a different one while being exposed to it for the additional 12 years she spent with Chronos, or Zen.
It might also be worth mentioning that all three of the sister's names; Aigis, Metis and Labrys, come from the greek language, as well as Philae or Rei by that logic.
