Hmmh, I love thinking new ideas I Just don't have any idea how skilled your developer is... I'll think about something fun.
Instead of war zone where you destroy some statue to conquer the zone, make CTF. Place flag to center of the zone and 1-2 capture places to edges of the zone. (or even more hardcore: Make the clan cap the flag to their castle). When player picks flag, he cannot use any skills. Slow his speed down dramatically, if the cap zone is near. Also remember to make the flag carrier incapable to use scrolls and he shouldn't be able to be summoned. The clan who owns the zone, will gain what ever you wish. For example, access to epic bosses, reputation, bonus stats(kinda controversial) or what ever you wish.
If the flag must be capped to castle, it would also focus pvp to castles and actually everywhere in the l2 world. Flag must be seen all the time in the map!
Make pvp based server:
*I will use imaginary numbers, no need to use them as they appear here, just examples.
Anti-feed system: Only players who have over +4* items, will gain status, which allows them to gain and lose pvp points. You will lose a point if you lose a pvp fight.
Item enchanting: Stealing enchants from other players - by killing them. Raidbosses also drop enchants. Example - If I kill a player who has approximately +3 equipment and I Have +0 items I will gain randomly +1 to 1 equipment and the killed player gets -1 enchant to random item. If both players have +0 items, there will be no changes. Everyone has only the set which is given to them on the character creation. If you are not in a clan you will not gain enchants. You can't gain pvp points from clan/ally members.
Raidbosses - shown on map - respawn time -> pvp over the boss. Drops small number of enchants(tradeable). (This will start the progress of enchanting since everyone has +0 items at start)
------- > PvP is the way to progress on server, pvp ladders work without feeding.
That should solve the fact no one PvPs. Also the forum system needs an addition: Simply forbid insulting server properties in global, make sure everyone understands that you are supposed to use forums.
Raidbosses spawn points and time are announced automatically -> PvP over raidboss. Spawn area whole l2 world -> more focus on all content pvp - not just farm zones..
Cancel skills -> debuff which locks down couple buffs for xx time. No more rebuffing and annoyed yells in globals
Best pvpers rewarded every x time, only kills count - if best player has healer in party - reward will be divided evenly.
I will think about something better - will post here.