Warhammer 40k III - Hats for the Hat Throne

[Cheesegear]

Blessed Weapon is +2 Strength Power Weapon, thank you very much. But needs two hands to use. Tool up for 'Living Saint'. Have you got the Witch Hunters Codex?
Canonness' rock around with 2+ Invulnerable (although it eats faith) and a Jump Pack, with Strength 5 Power Weapon attacks. Litanies of Faith and Book of St. Lucius. A Mantle is handy as well. All that comes in at under 150 points IIRC...Away from Codex.

If you're afraid of armour, strap an Inferno Pistol (read; Melta Pistol) to your Cannoness with Jump Pack. Although Melta Bombs are cheaper.

Inquisitors can be taken as Elites. But, no. You're only allowed the Land Raiders in your Codex. No Redeemers.

Sisters...Meltas are useless unless you're up close. Get Rhinos. Sisters can pack two special weapons, so, you can double up on Meltaguns. If you don't have Rhinos, go for double Storm Bolters. Acts of Faith can get them Rending. 20-woman squad with three Storm Bolters (the Superior has one too) makes messes. 'Drive-by' squads do the same, except have Rhinos with two Storm Bolters.
...5 Storm Bolters and 7 Bolters is scary for most Infantry. Marines not withstanding.

The only Heavy Weapon Sisters can take are Heavy Flamers. Again, need a Rhino to make any use out of them.

Sisters (and Space Marines, for that matter) don't strictly need Heavy Bolters. See above.

Heavy Bolters are reserved for Celestians, Retributors and Immolators. As a predominantly close combat unit, Celestians should not take Heavy Bolters anyway. Speaking of Celestians; they aren't that great. They have a sweet rule that lets them hit on 3+...Except against Independent Characters (yes, even if they have joined a unit) and Monstrous Creatures. Just about everyone else has WS 3 (excluding Marines) so you'll be hitting on 3s anyway.
Pass on the Celestians. You're missing Fast.

Strap a Jump Pack to your Canoness (or a pair of Wings if you're feeling Angelic...See Seraphim next...But, I don't understand it, since that would make a Canoness a mutant and her Order would be forced to burn her...) and grab some Seraphim who have access to Inferno Weaponry and Melta Bombs. Since Seraphim also have two pistols (twin-linked Inferno Pistols...Goodbye Armour), that gives them an Extra Attack which, makes them better in Combat than Celestians.
Did I mention that Seraphim give +1 Leadership to surrounding units for looking like Angels?

Dominion Squads are awesome. Drop your Meltas on your regular sisters squads (and pack more Storm Bolters and Flamers), and start packing four meltas on your Dominions. With an Immolator, who also has a Melta. Although, with a single-role unit like that, you're woefully unprotected against not-Marine Infantry. Best to slap on Heavy Bolters or the good ol' reliable Death-Flamer for your Dominion Immolator.
(Dominions must be mounted in a Rhino or Immolator).

Rule 1 of Sisters; Never too many Exorcists. Unless you're against Orks, Eldar, Guard or Tyranid. Then, swap 'em for Retributors and kit out with four Heavy Bolters. I fully support more Exorcists. Penitent Engines are fun. But you need a Priest in your army. Which, isn't a bad thing, don't get me wrong, since a Priest in a Repentia unit is not only fluffy, but makes them awesome.

...NO! Canonnesses can not join Repentia. Repentia are nutters. No-one can lead them except for Priests.

EDIT: Ninja'd on the Blessed Weapon and the Repentia.