So, onto this sovereignty matter and the use of ritual.
I was on the bus home today and the Catholic mass come to mind – as it can do at times – and especially the part with the Eucharist and holy communion. It appears that this really is the crux of the mass – and something similar features within Wiccan ritual. It is if you like, the part of the mass that the mass has been created for. It has purpose and of course meaning, it could be said it is the legacy of JC himself and what he was building up to (certainly in the case of Catholicism). And so it is that every Sunday (or Saturday evening if you were more into that kind of timing for your masses) that this element of the mass recreates something that was first established by the son of god himself, he explicitly requested they do this symbolic ritual in order to maintain the connection between God and the faithful.
This re-creative thing could be something upon which to build in terms of a ritual of renewal of sovereignty. Something done in a group setting, where the group collectively renews the sovereignty bestowed onto them by the goddess in question. This renewal is for both group and individual renewal. I cant see how the place of a sovereign can be established and his function fulfilled, I suppose this is one of those changes made to older ideas to be more in line with the 21st century we all live in, not to diminish the process, but more of adapting to work in a modern world.
The question really is; how do you know if Rigantona has granted you sovereignty? Do you assume she is hunky-dory or go in for divination of some sort? I can envisage some sort of divinatory event or events in which the 'message' is transmitted, and if favourable a feast prepared when the tribe gather. Foods cooked by those attending brought together and cooked - perhaps a loaf of home made bread in the form of a horse is included – and the finest part set aside for Her. Offerings of food and drink are made; what we have received from the and, we now offer back to complete the circle. The horse is killed, it's head dipped into red wine and offered. The rest torn up and shared between those attending. In doing so we have offered back what we have taken in hope of the obligation of return in the coming year. We have taken the form of the land and torn her body up to be shared between us, we take her away as part of us only to bring her back again a year hence and once again remake the circle.
Simple, symbolic and potential a powerful and moving ritual if performed with fitting liturgy.
Interestingly while I was looking for some images to add to this I stumbled across this link describing a Siberian horse sacrifice ritual.