If I remember correctly, there will be an arena, but no in-world pvp. That would be Valorium.
Somehow, I see the pvp populace going down big time in the near future, as soon as adventure is released. Unless they do another war mechanic. I wouldn't mind that, maybe they could even add a concept where players can prevent quests, or siege castes (like control points, but more like a pvp raid concept.). That'd be epic, and something this server needs badly. Raids, like massive battles over structures and control. Ex: There's a castle what has been claimed by nub A and his party. So Nub A can use preset defenses, and the center of the castle is the claim. In order to raid, Nub B's group would have to first get control of the outer wall (like a control point,) which would allow the access to the gate (or someone can sneak in and open it) and then capture the inner section, and finally, hold the castle for a bit longer. Players who control the castle would respawn in it, like a graveyard. This would be something in adventure that would allow healthy pvp in a very fun and rewarding package.
These castles for sieges would be designed to promote a challenge for raiders, and an advantage for defenders, so that defenders will fight off raiders who may have a larger party. Maybe instead of a cp style control system, maybe a death count for the defenders, (Because attackers will respawn much farther away.) which would be presented as a percentage. This could maybe be an event. Would be very cool.