[PvP Areas]
In my opinion, there should be PvP exclusive area for Free Companies to settle their disputes.
[Castle Sieges]
For those who loved Lineage 2 PvP, this is something that should be considered. People might say "It might intervene with the storyline of XIV", but Lineage 2 has it since release, and it has not intervene with the storyline of each new Chronicles that was released if it's done properly.
[Player Initiation]
Using Lineage 2 as a reference of PvP essence, since it was properly implemented and it was done due to the community, not just the game mechanic alone. So instead of having to talk to some NPC to wait on the PvP queue, and then enter the deathmatch and exit with just some rewards, it's BORING. It doesn't give you the feeling of intensity and accomplishment, or to me, at least. Player should initiate the politic of war, and lay sieges upon the opposing Free Company and it's Alliance's castle or territories.
[Alliance System]
I am not quite sure if it had been said yet by the producer, but I'll mention this here as well. Again, as Lineage 2 have done properly, perhaps XIV should have their own version. Free Companies should be able to form Alliance with each other to share the gain and contributions they have put together as a community. This support the player community, and friendship. Also the politic of war, you pick your ally closely, and maintain a diplomatic relationship with them throughout the war.