Balance is what Lineage actually is. Elf relying on his DEXterity, and other advantages that come with race.
The world itself "balance" is misinterpreted. It is not about having an equal chance in PvP.
This is how a custom-pvp server should be made. 99% of the servers never got it.
You have to be careful with skills' chance.
You can not have a custom armor that gives 50% stun resistance, while the resist buff already gives enough resistance for a balanced gameplay.
You need to balance things a bit. This can be done by nerfing the resist buff - transferring a big percentage to the item.
If both of them give insane stats (item and buff resistance), your resistance will be above logic - having a higher percentage of 99%.
What have you done? You theoretically replaced a resist buff with an item - literally added a new item, and you haven't changed the stats in-game. Pretty cool, isn't? (the same trick must be applied to all stats)
Make sure you review classes' accuracy and evasion. You should miss no matter what, player or mob.
If your custom items have huge defense stats. Don't freaking do it!
Keep low stats in-game. Most of the chronicles are not designed/supposed to support huge values.
Your enchant system should be decent. Enchanted items above +8/16 are just insane. Don't do it!
Do not listen to players. They can only open your eyes to review things. Test everything by yourself, and then apply changes.
Do not make hasty changes. You should have an imaginary map in your head, like a pattern. Once you make random changes, you'll lose it.