Thank you kamui for your insight in this.
I can add to this that in a norwegian context the two sword ideal where jused by both the curch and the king/state in the late 1100`s.( I know this goes against your dating of the two sword idea from Unam sanctam from 1302, but in a book about the norwegian king sverre I read last year, and author mentioned the two sword ideology. I will try to find a correct name of the book and the author later. ps. not trying to argue here ) anyways, according to the "sverre book" the churc and the state where having a conflict about who where supposed to be above the other, both the arch bishop and the king writes( if I remember correctly ) a speach or decrea( cant remember exactly, please bear with me lol ) where both with basis in the two sword idea claims theire institution for having the right to be above the other. I dont know if any of you have heard of this conflict beetwen king sverre and arch bishop eystein. My understanding of your descreption of the two sword ideology resembles what in norway are called "the saint olav ideology", basicly it boils down to that saint olav is the eternal king of norway and because of this according to this ideology, the person who are functioning king are only occupying that position in the absence of saint olav( who have other and more important things to do ( you know playing chess with EL or whatever they are suppose to do up there in paradise ). Well the crux of this, is that since the curch is the institution who for a lack of a better word: repressent the saints, they are therefor in theire own eyes the true authority over the kingdom of norway and in the eyes of the curch/olavits the king is only a vassal who take care of the non-spiritual parts of the society. So I guess you can say that its my own countrys version of the two sword ideology as you described it.
ps. There is a huge possibility that there are plenty of grammatical errors and misspelling, sorry about that..
thanks again, this really helped to spark my memory about the subject. And if a missunderstood something, feel free to point it out.