Complex sentence: If one chose to become a "briugu" (hospitaller), one would have twice the normal property qualifications of a lord of whatever grade (and this can extend, in theory, up to the qualifications of a king).
Split into simpler sentences: If one chose to become a "briugu" (hospitaller). Such a person has twice the normal property qualifications of a lord of whatever grade (and this can extend, in theory, up to the qualifications of a king).