One of the main issues I see with PvP is the limited area that it can be done in.
It limits ranged attackers to be up close and able to be targeted it easy.
It makes more sneaky characters unable to hide and attack from the shadows.
It makes melee characters unable to run at people from behind.
It allows any casting class to hit a majority of people with large AoE attacks.
What I am suggesting is allowing yourself to toggle to a PvP mode in any place and be able to fight and attack other people who are toggled in to PvP.
While in PvP Mode all names over characters are hidden to allow sneaky characters to sneak around in combat.
The potential size of the area is much larger so range restrictions are no longer a limit and casters can no longer bomb 10 people at once except for in rare occasions.
You can only party with people in PvP mode
All chat updates are stopped except PMs(from pvp Players) and Guild messages and Party Messages.
Sneak and invisibility makes you actually hidden from people in pvp mode
PvP mode turns off on death or when entering a quest or building.
It has a lot more varied environments with actual expanses of water. High builds for snipping points, More places for cover for all characters, and other fun stuff(moving floors in cannith).
For an example.
You are running around in the harbour by the docks and a dwarf rogues sneaks up behind you out of the water and sneak attacks you turn around and attack him and kill him only to get killed by the artificer who shoots you from up by the harbour masters house who is then killed by the invisible wizard who FoD him from behind.