I dunno, but for me, a Battle Sister is not a Battle Sister because she has a boltgun and power armour, but because of her Faith. So if you just have a chick with a power armour and a boltgun, then I guess she wouldn't be a Battle Sister, but a chick with a power armour and a boltgun. On the other hand, the chikc with Faith will be a Battle Sister even with a tattered robe and a broken stick.
I think the Support Specialist idea is pretty cool, but then the Sister should have a custom Trait like the Ogryn to represent her Faith. In our homebrew Warhammer 40k enviroment, we have the following Talent to represent Faith (note: in that enviroment, there are no Fate Points):
The character gains a number of Faith Points equal to (Willpower Bonus + Fellowship Bonus)/2 (rounding down). The character may spend these Faith Points for various effects, called Acts of Faith. The character may spend any number of Faith Points per Round, any time, and the effects of the Acts of Faith are cumulative. Once spent, the Faith Point is lost permanently. At the GM’s discretion, the character may gain Faith Points by accomplishing truly epic and astonishing deeds on his own, but the GM may also decide that the character loses one or more Faith Points because of committing heresy or treason.
The character may call forth the following Acts of Faith:
- Blessed Might: The character gains +20 Strength and the Supernatural Strength (2) Trait for the rest of the encounter. Note that this bonus Strength counts towards the character’s Strength Bonus as normal.
- Pure Faith: For the rest of the encounter, the character is immune to Daemonic presence – both to the negative Willpower modifier and the Fear/Insanity/Corruption these creatures cause.
- Shield of Faith: The character immediately shakes off any and all Psychic Power effects (both friendly and enemy!) and for the rest of the encounter, any psyker that targets the character with a Psychic Power will suffer a -30 penalty on his Focus Power Tests or doubles the Warp Demand of the Psychic Power.
- Spirit of the Martyr: The character immediately removes 1D10 Damage (removing Critical Damage first) and all levels of Fatigue. He also gains the Supernatural Toughness (2) Trait for the rest of the encounter.
- Wrath of the Righteous: The character doubles the Damage he dealt and causes Critical Strike on any Damage rolls of 9 and 0. This Act of Faith only affects a single Damage roll.
- Zealous Faith: The character immediately recovers from Pinning, Shock and any Mental Traumas, and gains the Fearless Talent and the Supernatural Willpower (2) Trait for the rest of the encounter.
We call this Talent "Screw the rules, I have Faith!" for a good reason …