*Firstly don't join the Heroine to the Seraphim squad. The squad will lose the hit and run ability. Have her close, but not join the squad.
*Remove the frag grenades from the battle sisters. Your not going to charge anything.
*7x melta for the Seraphim
. Not possible. I think you mean TL-bolt pistols.
*Priest has to join a squad.
Not to sound harsh, but I think your list needs a total overhaul. Here's why:
*Lack of numbers.
*Lack of anti-tank. What anti-tank weapons you do have are very short ranged. It's going to be hard to by-pass an army to reach those tanks.
*You have one squad capable of shooting over 12". A priest will prevent one of those squads from shooting max range.
*Very vulnerable to close combat and shooting armies. (middle ground you'd be fine)
*Plasma pistols also have a chance of frying your Veteran leaders, though thats the least of the worries
*Major changes needed
-Dropping of the priest and arco-flagellants. Seraphim are your luxury unit. With two of them, you cannot afford to have the Arco's around.
-You'll need either another SOB squad and you'll want your Battle sisters to be at least 14 girls strong. This may mean having 6 girl Seraphim squads to make it possible
-With these changes, you'll still lack a long range antitank unit. If you face a Wraithlord or lots of armour, I'd highly recommend getting an Exorcist
