Not every Sororita is Sister of Battle. Adeptus Sororitas are under Adeptus Ministorum, and they are organised into several orders, like Order Hostpitaller, Dialogus and Militant=Sisters of Battle. Sister of Battle are not only military arm of ecclesiarchy, but they are also Chamber Militant of Ordo Hereticus, an equivalent of Grey Knights of Ordo Malleus or Deadwatch of Ordo Xenos.
And the RP will be more casaul.