Can you still proc sneak attacks with two handed weapons? I saw a Great Axe wielding Sanctified Slayer build and it looked really badass.
So in Act 5 now, about to do the Trial to become a devil. Might go back in time in Kenebras and then save Galfrey first though, because the dumb twat decided to yolo my forces into enemy territory.
I don't think Hellknight synergizes that well with Inquisitor at all. Giving up spell progression isn't worth it. Getting domain progression from a bug is nice though. Furthermore, as a Hellknight you'll typically want to wear heavy armour, but Inquisitors want to use at most medium armour so they can use Stalwart. You do get a lot of nice resistances as Hellknight, but that unlocks at level 9 which means you won't have greater bane or level 6 spells. Smite isn't useful either because it scales with Charisma and as an Inquisitor you want to go Acolyte so you can get Wisdom Scaling for your charisma, thereby completely ignoring that stat.
HKS would suffer from similar issues; heavy armour access is pointless, you lose domain progression unless you pick godclaw, you lose greater bane if you level up HKS to access their resistances and as a divine caster you wouldn't benefit from arcane reduction.
HKS as a cleric might be funny though; With godclaw you would have like 3 domains at your disposal + impossible domain. Its just that whatever domains you picks at a cleric wouldn't progress past 10 if you decide to max out HKS.