User blog comment:Western Gen/Speculations for Season 12/@comment-10990964-20140715130719/@comment-3496661-20140715131139

Felix said the NR pay him in alien weaponry, so maybe they collected Forerunner weapons  and "paid" him. In turn he gave them to his mercenary buddies. I'm not concerned about where they got it since RvB is loosely based on Halo canon anyway, but it is interesting.