Sister of battle figure, customized from the original cannoness model to have a two headed eagle and to be helmeted. Female warhammer 40k army.

Army Background (From Lexicanum, http://wh40k.lexicanum.com/wiki/Adepta_Sororitas):

The Sisterhood serves as the Ministorum's only official military forces because the Decree Passive rules that the Ecclesiarchy cannot maintain any "men under arms". This was supposed to limit the power of the Ecclesiarchy. However the Ministorum were able to circumvent this decree by using the all-female force of the Sisterhood.[Needs Citation]
There is naturally some overlap between the duties of the Sisterhood and the Inquisition; for this reason, although the Inquisition and the Sisterhood remain entirely separate organisations, the Orders Militant of the Sisterhood also act in a similar role to the Chamber Militants of the Inquisition, especially the Ordo Hereticus.[Needs Citation]