oh wow, those are incredibly legit! For the Inquisition operative, I'd potentially recommend building a vambrace-mounted ranged weapon onto the armour plate, Grey Knights style. Except smaller, sleeker, you get the idea. Could be something as simple as a two-shot arm-mounted short-ranged cross-bow. Could be a flamer or flechette blaster.
Has the advantage of not changing the overall silhouette of that part of the miniature when viewed from the front; yet giving some functionality to it , and helping to make him a more 'elite' style and versatile combatant. While at the same time , hm, this is where it might get a bit complex - as ideally you'd want a palm not holding anything on the right, so that he'd be able to put both hands into utilizing that *excellent* Custodes-inspired er .. glaive? voluge? bardiche? The pointy-stabby-also-axy thing.
Nice going with that and the shoulderpad from Custodes ablative plating. Might borrow those concepts for use various places. [I'm part way through a long and drawn out exercise entitled "work out how to do interesting and distinctive things with ~25 more Goliaths ... best one thus far has probably been an Afriel Strain] ; also good turning of what would otherwise be bare flesh into synskin or the like.
Alternatively, chuck a small red button on the top of that pistol-grip, and you've got yourself a detonator .. or possibly a teleport homer, something for his comms, orbital-strike-designator, or electronic car-keys.
Also, where's that head from? A Primaris kit?
Anyway, on the Ynnari ...
Wow, I didn't realize the Dark Elf blood bowl miniatures were that tall; interesting [I've had an unopened box around for the past .. five-six months because i kept meaning to do either a "Gangs Of Commorragh" side-side-side project, or some Kurnous-influenced quasi-Exodites for an expansion to our Heresy-era efforts]. Hellion head is a nice touch.
Personally, I'd have avoided the pink colouration. In combination with the weaponized shield, it gives off a bit of a Slaaneshi vibe, IMO - which is ironic, given his factional allegiance. It *might* be a potential way to show some form of tie back to his previous craftworld or kabal of origin, the colour you eventually go with ... could go for a more .. darker Altansar [i.e. Maugan Ra] style scheme of (darker) purple and bone on the raised armour sections; or change the pink to a crimson , maybe even as far as mauve - would still keep the 'sunset' theme, but transitioning it away from soft "red sky at night, shepherd's delight" to "there are blood-red and/or dying/drying blood atmospherics going on and it's freaking the hell out of me" sort of vibe.
[perhaps, like, a kind of palette you might get at the *other* end of things - the "red sky in the morning .. shepherd's warning" approach of varying grey 'pregnant' storm-clouds with a red sun shining through; more directly/overtly hostile and baelful, so to speak. [...] There's something i've partially been meaning to look into myself for another project around ... it's difficult to translate from Sanskrit, but "ruddy" colouration that's kinda reddish-(brown-?)grey ; actually, it could be interesting to do greys on greys for the Ynnari, or purple on grey etc. - with your painting style, you could totally pull it off!]
Of course, that may mean re-doing the lizard skin to another colour - perhaps a darker one, a black-blue with light greyblue scales?
Now, for the next question ... do you have some hidden reservoir of Inq28/Inquisimunda etc. excellence going on? I did a quick scan through your instagram feed, but it's mostly [very cool] Primaris marines. You've got a real flair for conversion-work and colouration, so I'm personally thrilled at hte idea that there might be more non-Astartes lurking about somewhere.
Vox Stellarum efforts:
The Unyielding Adamanticores
[truescale Astartes, auxilia, and sectorial AdMech; M37/38]
The Haunting Harii of Hvergelmir
[truescale Astartes ... and associates]
The Unification Wars
[truescale Thunder Warriors, (Proto-)Astartes, Army of Unification, Aegyptian-style Proto-Mechanicus raiders, etc.]
[Tomb Raiding for Fun & Prophet]
[truescale loyalist IVth, VIIIth; Agents of the Sigillite; VIth; and so much more; and Umbral's amazing Traitors]
The Worlds-Wide Webway
[(Dark) Eldar, Imperial Inquisition, an a-maze-ing realmweave of fear and wondermeant]
[some rather different Inquisitorial Storm Troopers, true-scale Fire Hawks, Black Dragon, Inquisitor and associates, etc.]
For Whom The Great Bell Tolls Thrice
[attempts to put the 'priest' back in 'tech-priest' with more-medieval mechanicus]
[the log that incepted it all - at least two Inquisitors, truescale Deathwatch, local enforcers, cultists, etc.]