Fear not, this is short and sweet.
Here's yet another take on a fan 'dex. Mine is more of a tweak than a serious re-write. In other words, the sort of thing
GW should do regularly with codexes

.
Going through the existing Codex: Witch Hunters, more or less in order:
Psychic Powers: disregard all references to cost; psychic powers are free.
Henchmen:
Warriors: No restriction on number of warriors in retinue. Heavy weapons are limited to three per retinue. This includes plasma cannons.
Chirurgeon: Confers Feel-No-Pain on Inquisitor. Two confer Feel-No-Pain on unit.
Light of the Emperor and Spirit of the Martyr: Replace "start of turn" with "anytime during phase".
Armoury:
Plasma and Inferno pistols: 10 points.
Eviscerator and Blessed Weapon: 20 points
All Combi's: 10 points
Jump Pack: Confers "Hit-and-Run" as per Seraphim.
Inquisitor Lord: 60 points
Priests: 25 points
Inquisitor:
Ld 9
Arco-Flagelants: 25 points. 3-12. Allow invulnerable save when Implant Injectors cause wounds.
Celestians: Any Celestian may take a Storm Bolter at 5 points. Add Frag and Krak grenades and Bolt pistols at no points cost. Imagifer 10 points. add option for Sister Hospitaler (confers Feel-No-Pain on unit). Hospitaler is 12 point upgrade (i.e. one Celestian may be upgraded at 12 points).
Sisters Repentia: Add Fleet and Feel-No-Pain.
Assassins: All: Add Feel-No-Pain. Replace Fearless with Iron Will (as Inquisitor Lord).
Callidus: Neural Shredder counts as a pistol. Add Preferred Enemy: Everything.
Eversor: Add Fleet and Furious Charge.
Vindicare: Remove restriction on special ammo.
Death-Cult: 20 points. 1-5.
Chimera: As
IG codex (points too).
Rhino: As
SM codex (points too).
Land Raider: (As
SM codex).
Battle Sisters: Veteran 9 points. 5-19. Add Frag and Krak grenades and Bolt pistols at no points cost.
Storm Troopers: Add Frag and Krak grenades, Hell pistols and close-combat weapons at no points cost.
Seraphim: 18 points.
Dominions: Veteran 9 points. Add Frag and Krak grenades and Bolt pistols at no points cost. Weapons cost same as Battle Sisters. Imagifer 10 points.
Retributors: Veteran 9 points. Add Frag and Krak grenades and Bolt pistols at no points cost. Heavy bolters 5 points, Multi-meltas 10 points. Imagifer 10 points.
Immolator: 50 points. Add smoke launchers at no points cost. Extra Armor 15 points. Heavy Bolters are free, multi-meltas 15 points.
Penitent Engines: 60 points. Replace armor values with T7, W3.
Karamazov: Remove Monstrous Creature and Strength in Solitude. Add Independent Character.
Celestine: Add Feel-No-Pain. Change Fearless to Iron Will (as Inquistor Lord).
That's it. What do you think?