fear is really only for very very fearsome creatures just not for humans he really shouldn't have it. This person is only fearsome through what he commands and his armies etc (your example only clearifies this) but that is not what the fear thingie is about. All armies in this game would generally be considered a thing to fear really but that also is not how fear is in this game.
awe.. could be for humans and considering his "flavor" you could do it (I wouldn't though), if you insist on using it I'd not go higher than Awe +0 (only very magical and beautifull creature shoud have higher awe in dominions.)
Holy 4 is already VERY VERY high and hardly ever seen in the game so I'd really lower it to that.
as llama said MR 18 is standard for pretenders and sort of needed else it'll become magixd to death to fast.
Lowering his base dominion is not what I'd do, a very holy thingie pretender usually has high base dominions (I'd sooner get this higher instead of the holy 6)
for a holy person pillage really shouldn't be there in this game only the most wild or evil pplz have that, most pretenders are a bit neutral so you can RP each way.
healer 20 or 50 is a much more common and more logic choice for a holy man, though not for an iquisitor I must admit
I'd not use gluttony for his retinue but rather the command to summon like 5-10 units on battle start and a same option to get them via a regular summon command (seem fitting that he can convert pplz to become holy avengers/inquisitors or whatever) seems more thematic.
Ps standard human encumbrance is 3 not 2, 2 is only for barbarians and lion tribes, pplz living in the wilds running all day so having better stamina, your pretender doesn't seem to qualify.
The fire sling is a nice but IMHO not really a weapon for a pretender , maybe you should just mod a nice weapon, some sort of fire staff, or just have him throw fireballs. or undead repelling water (some commander has that and I've always thought it was a nice feature)
The immortality thing also doesn't seem to fit your description though (sorry) since you say a new one comes.. but if he's immortal he'd have all the old ones afflictions etc.
To solve that you could make an immobile pretender which can have the command to summon this unit (if you make it unique) it'd fit your description more.
Well good luck with it, pretty sure you didn't want to hear all this but whatever
PS I don't think he's really overpowered though.