which items should I upgrade, to get the biggest boost.

Unless KMS is different, you should have 90%+ PDR ignore - 30% from Leafre set, 30% from Aria Amour passive, 30% from your cane. Then add on ambition and Avenger PVP title, that should get you to 100%. Other than that It looks like your glasses are by far your weakest point. Does KMS have 3rd tier eyes? Kenta Goggles, perhaps?

we do not have the monster book system.
30 from amour, 30 from weapon, 10 from luminous link, 5 from avenger title and 7% from charisma. 82%.
we have kenta goggles, but they're permanently untradable, and I'm thinking of changing my main to a blader, as they are vastly superior now.(and they have more skill inherit PDR)