Taking lore and Dark Heresy 1e into account, Skitarii themselves are quite unlikely.
Skitarii are not frequently used on planet that the Imperium want to keep due to their wanton uses of Rad, Phophor and similar weapons which tend to have a bigger repercussion on the surrounding battle fields. Additionally, while Skitarii are autonomous:TM:, they do for the most part always remain assigned to a Tech Priest Dominus.
As for Dark Heresy (which has been a large inspiration, baring the Ogryn), going with the different Classes: Looking away from the Admech stuff
Base Classe
Sub Classes
Alternate Classes
- Adept: On its own ill suited, same for most Advance careers
- Magister: Not sure on how the lore of it is meant to work, but for example give access to some Psyker stuff (Up to rating 3) [Base]
- Reliquary: Adepts entrusted with specific equipments (ranging from a Condemnor Bolter, Digital weapons and even to a Jokaero, not that this would work here) [Daemon Hunter]
- Daemonine Seeker: Adepts seeking the names of Daemons, imo not really workable here. [Daemon Hunter]
- Bonded Emissary: Not suitable here, emmissary of foreign powers (Inquisition, Admech, RT…) [Inquisitor’s Handbook]
- Xeno-Arcanist: Adepts with Xenos and Cryptic knowledge, being at time able to use Xenotechnology [Inquisitor’s Handbook]
- Legate Investigator: Not suitable here[Inquisitor’s Handbook]
- Demagogue: Not really suitable other than for a support ability [Salvation demand Sacrifice]
- Infil-Traitor: Not suitable, would have to have the character implanted in the Dreg/Scab factions [Salvation demand Sacrifice]
- Saboteur: Chem uses, Demolitions… [Salvation demand Sacrifice]
- Malefic Scholar: Adepts with some Warp powers and knowledge, but nothing point to Grendyl being a radical [Radical Handbook]
- Sage: Just Adept+ [Ascension]
- Sister of Battle: As base, kinda too strong, and not offering much other than Zealot with Power Armour [Inquisitor’s Handbook]
→ There could also be a way to make a Sister work on a different theme, by having it centre quite heavily around the Act of Faiths- Sister Hospitalier: Have Carapace armour only [Blood of Martyr]
Could see the Cryptic end up be about the older Agents embedded into the Hive (Cryptic: secret, occult; employing a Cipher); or even the Eldar (Cryptic: not recognised); rather than Admech (“Cryptic: employing a Cipher” being tenuous).