Saint Sabbat
"That which was will be.That which dieth will live. That which falleth will rise up. This, I say to you, is the nature of things, if you but once believe."
- – Saint Sabbat
"Sabbat Martyr"
- – a phrase spoken in reference to the Saint
Saint Sabbat, AKA "The Beati" is an Imperial Saint from M.35 and has been a prominent figure in the Gaunt's ghosts Series. She was described as a small, beautiful woman, with green eyes and short dark hair. She is notable for the achievement of going on a 105 year long crusade and conquering over a hundred planets in Segmentum Pacificus which would be named the Sabbat Worlds in her honour. She would later resurrect in M.41 during the crusade to reclaim the Sabbat Worlds.
Life and Martyrdom
Sabbat was born on the Agri/feudal world of Hagia where she was but a simple Shepard girl in her youth. However Hagia and the worlds around had a very chaotic problem, mainly Chaos. She apparently walked down from the hills and felt Big E himself talking to her, and considering what she did next he probably said something along the lines of "HEY, GO CRUSADE, IT'S GREAT". So with the Emperor's light guiding her, she built up an army and led a planetary crusade to wipe chaos, and multiple Xenos species off the planet. Afterwards she went on, what can only be described as a crusade high. She lead multiple Imperial forces into the nearby sector and began to conquer all the planets in the name of the Emperor.
She was so successful that she caught the attention of multiple Space Marine Chapters to come help her and the crusade and brought in many experienced and loyal Imperial personnel. After 105 years of spreading the Imperium's reach to the sector and making it a viable Imperial region in space, She finally fell fighting on Harkalon, where she suffered "9 holy wounds". She was was entombed upon Hagia and made an Imperial Saint. The region of space she had conquered was named the "Sabbat Worlds" in her honor and the rest, is history.
It's just a shame the Imperium never learns from it.
The Sabbat's World Crusade and Resurrection
Speed forward to M.41 and all the shit has hit the fan again. Most of the Sabbat Worlds had fallen to the Ruinous powers... again, so the Imperium finally decided to stop acting like an obese whale stuck on a hill and sort it out. The Sabbat Worlds Crusade was launched by the High lords of Terra under Warmaster Slaydo (later Warmaster Macaroth) to recapture the sector. After her tomb was personally defended by the Tanith First, she was resurrected but not really, but also kinda, and then she actually was.
Okay, let me explain, and listen because it gets confusing, The woman claiming to be Sabbat resurrected was just a delusional woman who, upon being reviewed by Colonel-Commissar Ibram Gaunt and a Hagian priest showed, she wasn't the Saint but they acted like she was so the Crusade's morale would be kept up. However the "false Sabbat" did do some things the actual Saint wanted to happen, that being asking for the Tanith First to come protect her and publicly announce her arrival on some back water planet so all the chaos forces in the area would come and try and kill her (it was part of a plan) so the real Sabbat might have been influencing her in some way. However at the same time some random Pilgrim girl is hinted to be the actual Saint Reincarnated, but she then dies, and then Sabbat actually resurrects herself in the "false Sabbat's" body, and this time she actually is Saint Sabbat Reincarnated.
TL/DR; Saint Sabbat Indeed does become Reincarnated and goes on to pull off a pretty genius tactical move and save the Sabbat Worlds crusade, from collapsing. After which goes on to help lead the Crusade from the Front line with the Warmaster.
The newly Resurrected Saint Sabbat is also a bit of a combat monster with her pulling off stuff like murdering a Fucking Baneblade all on her own, and fighting a Chaos Marine Champion while being surrounded by him and his personal guard and still killing him an taking his head. Suffice to say, she's pretty badass now.
Connection to the Sisters of Battle
Saint Sabbat, had a slightly confused relationship to the Sisters of Battle as in the books she was said to be the founder of The Order of our Martyred Lady. Ibram Gaunt also meets a Sister of Battle that crusaded with Sabbat (she was a ghost). Except this can't have been the case as Sabbat was born, crusaded, and died all within M.35, 1000 years before the Age of Apostasy, and the actual founder of The Order of our Martyred Lady was Saint Katherine, for whom the order was renamed upon her death.
In the Sabbat Worlds Crusade book this has been retconned (it could barely be considered canon in the first place) to an unknown connection to the Daughters of the Emperor, and it was also noted that a small group of "Sister Militants" fought alongside Sabbat as her entourage, with the "Sister of Battle" Gaunt met being one of these Sister Militants and he just didn't spot the difference. Since the new connection is largely unknown this new fluff gives us two possibilities of the relationship between Sabbat and the Sisters:
1) The Daughters of the Emperor where more proactive than originally thought, and would leave San Leor to take active roles in crusades and other Imperial conflicts, and they joined up with Sabbat and became her Honour Guard during the crusade. This is plausible but has it's problems, mostly that the Daughters were never recorded in Imperial records before the crusade or afterwards until the Age of Apostasy. This can be explained with the fact that they where were a very small force and there are entire Space Marine chapters who's origins are completely unknown, so a small force of all female warriors not showing up in Imperial records is understandable.
2) Sabbat formed the "Sisters Militant" that crusaded with her, and after her death the Sisters left the Sabbat Worlds, either to spread out across the Imperium or as voluntary exiles, and formed the Daughters of the Emperor eventually settling on San Leor. This seems like the more plausible as being formed by an Imperial saint and acting as her bodyguard would help explain the Zealous nature that the Sisters displayed even before they where found by Goge Vandire, and would also explain why the Daughters only show up twice in Imperial records. In addition Sabbat is associated with the Fleur-de-lis as it is shown to be her chosen symbol, which would explain why it became the symbol of the Sisters of Battle. If this theory was true it would mean that the Sisters could trace their origins back to Saint Sabbat. Especially if you consider Sabbat essentially being Joan of Arc in SPESS, and her successors being sorta-kinda French with the whole Fleur-de-lis thing. Not bad for a wee farm girl born in no where space.
Playing Sabbat in Game
It's fairly safe to say that "The Beati" won't get herself a model, despite being one of the most popular Saints in 40k Lore (no small part in thanks to the Gaunt's Ghosts Series), so if you want to play her on table top your best bet would be to convert Saint Celestine's model and use her rules (come on GW, no generic living saint rules?)