Actually, in case you're all behind in the lore; AhHgem, they are all secretly the "daughter" Custodes of the Emperor. They don't really fall in battle so much as they all become living Saints who dwell with the Emperors Mother Goddess of Humankind, and most power Chaos Goddess, within Her realm of Non-Reality.
Umm no they’re the most loyal and faithful normal human soul that through their faith are empowered by the God Emperor The more active and powerful he is, the greater the feats the sisters can achieve… their souls go screaming into the warp like everyone else in death unless Big E singles a sister out to save her soul
Can't wait till a Space Marine identifies as a woman and join the Sisters of Battle, then is immediately put in charge because SHE is the best of them.
What would happen if one of the sisters of battle saw a female custodian? Their minds would be blown and they would definitely try to make that custodian a new Saint or something.
The sisters are known to be devout worshipers and the Custodes are bound by the Imperial truth. This can only result in the next heresy. The Scissor Schism👉🏼👈🏼
They would treat them no different than any other custodian because gender nonsense is a 21st century problem and nothing they worry about in the 42nd when dealing with transhuman posthuman super soldiers.