A lot. A whole lot. Ignoring the major stuff that would either change the direction of the game or require EXTENSIVE coding or basic MOAR STUFF ... my main change would be:
- Individual Reputations
I think individual pirates should have Reputations we can see. Not just what their guild ranking is, but information about the pirate - especially their PvP info (more on this later).
- Ship Flags.
I think that ship's should have flags that we can view from afar to see what they are and determine a bit of information about the ship.
If you are sailing on a particular quest - then your flag would show that of the guild you are working for and what rank you've achieved in this guild. This might help us determine what cargo that you might have.
Additionally, I would implement it so that in order to engage another vessel in PvP - you must raise the black. This is also the case with land-based combat. The ship MUST have raised the black.
Then I would tie this together with a Bounty Hunter's Guild. This is the part that would take extensive programming.
Each pirate would have a certain reputation with the Bounty Hunter Guild according to their PvP history. As a player engages in piracy, their bounty goes up. The aggressor of piracy attacks will be determined by which vessel has raised the black (in the case of both vessels - neither gets reputation or both do).
There will be two ways to reduce the bounty - pay it off by bribing the Bounty Hunter Guild or dying at the hands of another pirate. Dying will only marginally reduce the bounty and never fully eradicate it.
The piracy bounty will be a semi-permanent effect in that it isn't session specific. It will persist regardless of logging out or length of time it has been in effect. The only way to remove the bounty completely is the one listed above - bribing the guild.
I believe this will add some dynamics to the PvP game without removing it. It will make it more realistic in that pirates were hunted men - and those that engage in it will eventually become wanted men.