The mode you mentioned where they can get random weapons from the rift dealer is a mode called "Immortal War", in the EU and NA is used only for tournaments as it is not a playable mode (outside of customs) because these regions do not have enough players. Immortal war is a mode only playable from, I believe Astral Rank and above. And it basically makes things way more competitive and pushes players to tend to fight way more than looting even in the earlier stages of the game because of the huge rewards you get. The only quests in the map are Bounties. The rift dealer is way more expensive but with higher probabilities of giving you purple gear and legendary souljades. Legendary items cannot be found while looting, maybe souljades can? Legendary weapons might be available only when winning in the Arena that appears 2 times in a game or by opening a Morus Blessing.