Looking at the available professions from both the core HARP book and the expansions I have, Diomin's shaman is looking similar to the Thamaturge, especially in what the effects of attaching spiritual significance. The shamans on Diomin invoke their spirit magic mostly through ritual, and some abilities have effects similar to existing spells.
I'm considering Co+SD for the shaman's casting stat combo.
That said, all versions of Attach Spiritual Significance are similar to the Imbue spells. Differences are: there will be no additional PP cost to attach spiritual significance to an enchanted weapon, the ritual IS the prep, duration is the lifetime of the user, effect can only be used by the proper owner, does not register as enchanted (unless also so), and base item user is assumed to be the caster.
Scaling Options:
Target User (1 other person): +4 PP
Target Users (group): Additional PP depends on size of group. Groups can literally be any size, including an entire nation.
Characters using the See Spirit talent will see Spiritually Significant items as an extension of the user's own spirit over the item, with the size of this extension depending on the power of spiritually significant effects on the item.