Any faction rank 2 unlocks the ability to buy armor within that faction. While impractical you could grind enough marks (200 weekly cap) to buy 2 pieces from that faction. Any faction rank 3 unlocks the ability to buy weapons from that faction. Dont worry about it. Just focus on one aspect to push to rank 2. That means make sure your keeping the same class item equipped too btw. You start changing that you might be inadvertently rep jumping back and forth. 24-26 catches a lot of players and slows them right down. Again dont worry about it youll get by shortly. Best part is once you creep past rank two youll be landing purple gear in a windfall.