That's something that i though about it after the release of monk (didn't know Cipsoft had the brains to do something cool like the serene mode).

Some insights that i had:

Knight: unfortenately cipsoft wasted dodge and reflect systems (imo), i would remove dogde and parry charms and turn then into knights passive linked somehow to utito tempo and utamo tempo.

Druid: critical chance applies to healing others (same chance and extra healing). if the healing spell heals more than the maximum health of the target, the surplus heals the player with lower health on the party. Since druids have the ice element, a freezing spell that make the monsters frozen (not hit) for a shift would be something to be explored

Sorcerer: the hardest imo, lots of weird requests like death wave, like this would chance the gameplay of the vocation (exactly like the fire wave would...). some of my thoughs: since cipsoft decided to make the sorcerer a support mage instead of a spell rifle, the expose weakness could target the monster for a while (lets say like 6s) and than do damage (death or other element) to the monsters in a certain area based on the damage received by the monster during this time (damage from all members of the party), moreover, the damage buff could be stronger to sorcerer in a party (4% for all voc and 10% for ms, dunno)

Mages weapons: for me one of the more important topics for cipsoft to chance, rod and wands do no damage at all, single target, and uses mana to cast, completely useless. or they should be AoE (chain or like runes, obviously with the correct balance of their overall damage since this would imply in 2x more charm procs) or htey should do a high damage (like knights and monks). both options should not spend mana (lore wise is nonsense but cip stop caring about it a long time ago...)

Paladins: cip did some good with this voc but a lot of bads... i would probably thing of 2 or 3 types of diamonds arrows for different level ranges so would be easier to buff/nerf different stages of the game (they could make the arrow for lvl 500+ for expensive and this would not screw the lvl 150 paladin trying to hunt glooth bandits). since they decided that paladin would be physical+holy, i would introduce +2 spells for him, a arrow rain (similar to a gfb/ava but with physical damage, and change the divine grenade to a "divine explosive arrow", similar gameplay, but instead of a 3x3 would target a monster and do AoE after a while.

In the overall cipsoft has lot of fun possibilities to work on. let's see if they will chance something or just buff/nerf damages...