Saint Anais was a Living Saint of the Adepta Sororitas who fought in the War of Faith in the Kaurava System sometime during the late 41st Millennium. Her origins, which of the Orders Militant she originally belonged to and how she rose to sainthood within the Adepta Sororitas is not known.
Saint Anais was placed by Confessor Turgenum March alongside the Order of the Sacred Rose in the defence of the Order's primary bastion in the Sama District, on the planet of Kaurava I. When in battle, Saint Anais was imbued with the "Inviolable Aura" -- a powerful psychic aura which rendered every Battle-Sister in her presence nigh invincible.
However, this gift had one flaw, for if the holy shrines used as the anchors for the faith that provided the blessing of this powerful aura were to be destroyed, the Inviolable Aura could be rendered impotent. This made even the Living Saint subject to mortal wounds and allowed her to be slain -- for a time.