I agree with the Exilia's suggestions except the Harmony part. There is a reason that DDI is capped at 60% for seasons after SS6. One you hit 60% DD, you can makes one or two SD ratio Increase items to counter the SD decrement Increase from weapons/staff. By default of this server, 85% damage goes to SD and 15% damage goest to HP. What SD decrement increase by 10% does is that once the attacker has this option on his weapons, 75% damage goes to SD and 25% damage goes to HP. That's a big improvement in term of damage. Reducing the Harmony option would be a huge buff to dual-wield characters who can make SD bypass and SD decrement at the same time.
Regarding the server, I have a few suggestions:
Improvement in PVP and Gens PVP, e.g., reduce exp in relics and karutan 2 a bit and boost exp in vulcanus and swamp, one or two more death king invasion, able to join DS BC IT with 1 pk status, weekly mass PVP event like "The Purge" where everybody is free to kill, etc..
Making jewel dropping rate depends on the size of the party to reduce jewel farming.
Nerf zen farming in Kalima maps. I was wondering why some players can farm so much zen.. Right now I'm doing it too but a little bit late to the game. Nerf it next season please.
For each boss, you only earn credits and drops for the first 3 kills only. I'm tired of seeing Coco and Catarina everytime. Leave some for the rest of us.
Only allowing upgrading 2nd wings with credits to +11. This is to make 3rd wings worth something. Right now a 3rd wings for summoners does not worth as much as a 2nd wings+12+opt..
Just my two cents.