The PvP rules here have worked for years. Killing someone does not clear memory, this will force you to have to figure out better ways to conflict.
You can also not learn anything about what happened as a ghost.
The grace period kinda does exist, because you are not allowed to seek out PvP for OOC reasons, which it would be if you where just clobbered.
You are not allowed to PvP around NPCs, as that ignores NPCs, but you are also not allowed to use NPCs as shields to protect you if your picking a fight