My background and experience in world pvp & arena is the extreme high end, from rank 1 to top 10 in arenas and sweaty open world pvp with the guild. Anyways, lets make this as short as with regards to suggestions:
High Risk pvp:
On death you drop loot that is in your bags & a set amount of gold. This feature was core to why a ton of people played on Ascension, It was fun & risky. Go out and farm a ton and someone comes and kills you and you drop between 20%-30% of your loot in bags felt bad, you wanted revenge and this created drama and a community around it. It was FUN! What an MMO is about at its core!
Open world Caches:
Spawn every few hours and drops incredible loot, The system from Ascension was great. I remember many 40v40v40 battles over these open world loot caches. Unlike anything I have done in retail or other servers - It brought people together and also created that community drama and nostolgia from back in the day.
I am not going to flood suggestions as it can get long but the above 2 are the absolute core of incredible PvP and community fun. Please add High risk!