So right now, everyone remotely interested in PVP is going to be an emissary for Reaper faction and trying to hunt down anything they can find, which will automatically result in quite a bit of frustration for others. I love mechanics that drive PVP interactions personally, however I am a little bit surprised that no counter-balancing faction was introduced together with the Reaper Faction.
What I am thinking of is in the vein of a "police" force, whose task it is to collect specifically Reaper's Bones emissary flags. Lore wise it could be explained with the other trading companies hiring someone to protect their emissaries during their travels.
My first thoughts immediately went to the Sea Dogs venturing into Adventure, being hired to hunt down the Reaper's Bones emissaries. They could for example level up with handing in anything/heroic acts (as do the reapers now, except not for sinking trading company emissaries) and then, upon reaching a certain emissary rank, be able to see all Reaper emissaries above emissary rank 3 on the map. Obviously this needs to be tested and balanced properly, however I feel like it would be a good incentive for people with the desire to play "clean" PvP and not just hunt down anyone they can, whilst also making Reaper's Bones gameplay more difficult and skill based.
Of course I completely understand if the Sea Dogs are to be kept strictly in Arena to enable Arena players to identify with the cosmetics they have achieved by playing it... I suppose in that case other factions could be invented.
