I typically pronounce sedes as SED-ays. However, I recently noticed that the "Holy See," meaning the bishopric of the Vatican, comes from Sancta Sedes (the Holy Seat), so if this is being rendered "see" in English, then the suggestion would be that it was originally pronounced SEE-dees, not SED-ays, at least in post-Renaissance ecclesiastical Latin.
Are there any definitive tracts on the pronunciation of this word type?