PvP is awful here. Classes are so broken against each other that they get an entirely new set of abilities when they enter PvP areas. This means you cannot have Open World PvP. Can you imagine trying to cast Fire IV as a BLM to fight off a NIN? One stun and your cast is gone which starts another cast timer as you try again. Sure there's Triple Cast, but I doubt you'd finish off the NIN before your three spells were up.

But then, if you did manage to ambush a NIN, it'd be a different matter altogether and the NIN player would cry at the unfairness.

Open World PvP would require a complete rework of every single class in this game- all abilities would have to be scrapped and redone from the ground up.