Spiritual (or Astral) Rank
 

Shamans and similar folk interact with spirits as the central part of their role, or perhaps the whole of it (at least in settings that have spirits or spirit-like entities, whatever their power source is). If those spirits have an organized hierarchy, it's possible that some shamans et al might be placed in that hierarchy themselves, thus potentially having Rank or Status that only matters to spirits (and the mortals that interact with them enough). In most cases, this probably involves having a Patron who gave you your Rank, and a Duty to said Patron.

The spirits themselves would also have ranks in such a setting, which would have a variety of effects even if your shaman doesn't (perhaps you have a spirit Contact with Rank 3 who gets promoted due to something you do for your Contact in-game, giving you access to greater favours... but also giving the spirit greater and stranger responsibilities).

How much the Rank costs depends on many factors, including campaign-specific ones, like how much the spirits are going to interact with mortal society beyond granting powers or causing trouble; treating the advantage as a variant of Courtesy Rank may be perfectly reasonable in some games, while others might need the full five points per level, for what is otherwise the same character (along with all the other reasons why Rank might not cost the same, of course). The number and names of the ranks would likewise vary depending on the types of spirits involves, and how they are organized (e.g. your Rank is respected by the spirits of the forest, but river and city spirits don't care in the slightest; likewise, Rank in the Summer Court may be a problem when you have to interact with the Winter Court, if diplomatic relations are breaking down - which may also bring your Duty to the Queen of Summer into the adventure).


Thoughts?

Re: Spiritual (or Astral) Rank
 

As you say, would depend how the spirit world is organised in game - if it's something like a Voudousaint or Shinto interpretation with solid power structures then rank seems solid ... albeit then you're looking more like a priest than a shaman.
But a lot of portrayals have a pretty unorganised spirit world - maybe due to a lot of animist cultures being more or less tribal themselves - and so rank might not get you very far (again, much like your rank in service to a local human strongman might not get you very far outside his immediate domain). There reputation might be more of a thing.
Still, shamen being an integral part of a spirit heirarchy seems solid if one exists - especially if ancestor spirits are a big thing - at which point, the difference between a living shaman and a dead one might be pretty minimal as far as the spirits are concerned.

Re: Spiritual (or Astral) Rank
 

Thomas Aquinas explains the detailed hierarchy of the angels, as including nine ranks: angels, archangels, principalities, powers, virtues, dominations, thrones, cherubim, and seraphim. This could be mapped onto the GURPS system of Ranks 0-8. In Aquinas's system, the lowest ranks deal with human beings; the middle ranks with the order of nature; and the highest ranks with God.

Re: Spiritual (or Astral) Rank
 

I talk about it briefly in GURPS Template Toolkit 4: Spirits.
In my opinion Rank is only suitable if there is an established hierarchy. So Angels, Demons, a beurtacit society of spirits like Chinese celestial, etc.
Status is more likely and typically based on power and age, though sometimes a spirit may have an outsized level of Status.

I had planned on going into this kind of thing in more detail in a pitch I made earlier this year but have to wait to make the pitch again and even then I am not sure it would be accepted.

Re: Spiritual (or Astral) Rank
 

Bear in mind that this sort of thing is exactly why Social Engineering: Pulling Rank is a thing, with the Patron being implicit in the Rank. And when deciding the pricing of such things, Spiritual Rank almost certainly involves a patron with Special Abilities and HighlyAccessible: in terms of Pulling Rank, if any sort of Rank should give access to Supernatural Aid (p.17), it would be Spiritual Rank.

Indeed, depending on the nature of the spirits in the hierarchy, I might even be willing to bend on its recommendation that supernatural smiting and spirit summoning not be allowed as supernatural Fire Support and Muscle, respectively. In effect, Spiritual Rank could be used as the basis for a magic system, essentially by applying Pulling Rank to Divine Favor instead of a mundane Patron (replacing the Petition and Reaction Rolls with an Assistance Roll) and suitable to followers of a god who makes extensive use of angels or similar spirits as intermediaries rather than getting involved personally. Something vaguely like In Nomine, for instance.

And yes, this would be more suitable for priests than for shamans; I would almost certainly require Clerical Investment as a prerequisite for this kind of Rank, and would have it double as Religious Rank. For Shamans, I'd be more inclined to use Social Engineering: Keeping in Contact as the social mechanics serving as the basis for their magic system.

These differ from more traditional Divine or Spiritual magic systems in that the spirits involved are more directly involved in the world, instead of being abstracted away and kept behind the scenes: campaigns where Template Toolkit 4: Spirits or the equivalent sees regular use. That said: much like Learned Prayers in Divine Favor effectively couple a Divine Power to the Divine Patron, I could also see Divine or Spiritual Powers similarly coupled to supernatural versions of Pulling Rank or Keeping in Contact.