Expecting this to get a lot of mixed feedback because a lot of the awful pkers on here rely on some of these broken mechanics and features to remain 'competitive', but here goes anyway.
Make Void break on death (I believe this is something already being worked on as a clanmate suggested it previously)
Incorporate The new Staff as an item that can be obtained only from PKing, perhaps make it a 1/500 chance, or an 1/250 from 100% EP.
Add rag protection (To stop people returning in nothing but Dhide and bolting when people are out in the wild, risking a fair amount)
Make EP increase quicker based on amount risked/wealth, will influence more players to risk in the wilderness, making it fun for everyone trying to pk and get a juicy kill.
This is already a feature with Rev caves, but try put a Significant increase on Money per hour from activities inside the wilderness, rather than outside of it.
Fix battle mages, and remove the battle mages that are outside the arena. (You can currently attack them with any combat style)
For some reason every single NPC in the wild is aggressive? This has a really negative impact on team pking, as it's incredibly easy to tank a couple levels and sit in 30 Npcs that should not usually be aggressive, takes little to no skill/wilderness knowledge.
Nerf the Lime and Lava whips slightly in PVP, you see way too many 40s-50s+ against tank gear when the user with the whip has very little bonuses/bad gear.
The client is awful, I'm not sure if there's a memory leak but after being open for so long you will randomly DC, sometimes this happens in combat, you can even feel the client getting clunky over time. If you'd like help identifying the cause let me know, I develop myself.
Too harsh of punishments - I believe for such a small community your punishments go above and beyond what is deemed to be necessary by a large amount, this isn't just for me, or my clan mates, this is my overall opinion.
I probably forgot a few things, but let's just leave it here for now.