Conquest Concept
So this was an idea I was kicking around after the Live Letter's interest in PVP and an LBR episode discussing this. But what if we brought a conquest like system in this game, and in areas that are neutral or not controlled by a nation, there can be random flags and event anouncements for those in that area to que up for a PVP match in that zone. People not participating can watch it and become untargetable, but those in it can have a PVP match for control of the zone.
How can you justify this by lore??
Make it so that the nations allow grand companies to do these exercises and fights to maintain the peace and unity of the nations, and easing tensions by allowing these exercises. These exercises allow nations to maintain peace by alternating governance of areas in a manner that is equal to all to obtain. Many games have used this as an excuse for PVP and it isn't much of a stretch.
The Perks of such a System?
You can give people a sense of nationalism for their nation that is desperately lacking in this game. Currently nations are picked mostly based on their glamours or even more so how close the market board is to the warp. That is a real bummer considering what this game is capable of. So I propose that with each are that is controlled by your grand company, you gain bonus exp, gold, and allied notes from fates. Also you can get cheaper teleports, vendor items, and cheap or free mending in a zone your grand company controls.
This would give a lot of incentive for people to want to control a zone, but also give people a sense of purpose that their contributions are actually affecting the world we populate, rather then feeling so distant from it. People in areas that are not under their control will get the same prices they get now, just those grand companies that do control certain things will get additional perks.