In other words, using short-term magic items to create long-term or permanent ones. Sorry about the title, I couldn't think of anything short enough that wouldn't be too vague or misleading.
So, it seems like this should be possible within the rules as written, but it is a bit weird. Perhaps you're not an Adept, or are not a full Adept, and either can't get the spirit to your Ritual Space, or can't get the item there (or both) or don't need ritual space but can't do a long enough ritual where the item or spirit is, or some other such issue. So, you prepare a charm or other conditional ritual based on the strength you believe the spirit has, and then you or someone else go to where you need to be and activate it (and hope that you estimated correctly, because changing this on the fly would be much harder, I think). The questions I have are how much, if at all, the rules would need to be fudged to allow this, and what would be the consequences for the game and setting if it is allowed (which helps GMs decide if it should be)? I'll give three examples (assuming they all fit in the post), one for Fetish and two for Embody:
1. You want to trap a particular evil spirit in a fetish (and maybe your style doesn't include Spirit Trap), and are unable to summon it to your ritual space, but you do have a pretty good idea of how powerful it is. Thus, you prepare a fetish ritual for it, packed into a charm, and go off to the haunted house to confront it.
2. You want to Embody a trickster spirit in your annoying neighbor's car. Obviously you can't take the car to the Sacred Grove you use for rituals, but you can certainly walk past and use Sleight of Hand to slip a charm into a gap in the bumper, and leave it to activate at sunrise.
3. A strategic magical weapon: Imagine a
leaflet bomb loaded with Embody charms. It goes off over an enemy city or military unit, and any charm that hits an appropriate body Embodies a spirit in it. Depending on how the rituals are done (you need a lot of casters for something like this), some or most will not do anything immediately, or at all, but enough could to make a huge mess (and if you do have enough casters, each Embody charm or small groups of Embody charms could be paired with other charms that guide them to useful bodies - e.g. the graveyard or morgue, if it's too close and not properly protected). This seems like a Modern Fantasy one, but could be done at lower TLs, using a catapult and a timed spring-release mechanism, or yet another conditional ritual.
Number 3 especially would be unacceptable in many games, but there are probably some where it would fit quite well, either as a current weapon, or a terrible relic of the Great Mage War (it would not need to be Embody charms specifically to be devastating, fire charms in a medieval city would be quite effective, but that's more for a 'Strategic Path/Book Magic' thread).
Thoughts?