From Warhammer 40k - Lexicanum
Soul-guardians are an Imperium organization of Blanks, that use their abilities to defend the Imperial Palace on Terra.
It is among the groups, that the reestablished Sisters of Silence have begun giving Blanks to. These, however, are only the Blanks who did not meet the criteria to join the Sisters' order.
- 1: Codex: Adeptus Custodes (9th Edition), pg. 37 - Silent Vigils