Hey PA it's me again, I've been kind of bored lately so it made me want to retry playing every class in arena again and here's what i found. 

I hope it helps with the current class balances.

Solaris

(As a somewhat female version of Titan/Destroyer she badly needs more protection,

she's too bad in arena due to her lack of immunity)
-Remove Super Armor in arena from skill Call of the Dragon,

and add Super Armor in Arena to either Infernal Purge or Lava Surge instead

Windwalker
-Remove wind-up animation of skill Wind Slicer
(The wind-up makes her combo feel clunky, and slow in PVE)
-Reduce cool down of skill Gale Harvest from 8 to 7 sec
(She does not stand a chance against Sura when they have almost the same type of skills augmented with super armor)

Lupa
-If the skill Divine Roar's Flow: Claws of Rage is activated reduce skill cooldown by 1 sec.
(It does not make sense when the main skill has more super armor duration than when its flow is active)

Archer
-On skill Snapshot, let Archer fire 2 bolts of arrow before and after he moves and,

let him move backwards when there's no directional key input.
(He always gets caught first before he can even fire his arrow in the arena, because he modifies his stance first.
If you clash Archer's Snapshot at the same time with Fletcher's Keep Away or Huntress's Blasting Gust,

Archer will get CC'd first to either one of the two)
-Fend Off skill is too clunky
(It wont work well unless you chain it with an evasion)

Sage
-add skill chain between Judgement of Ator and Spatial Collapse
(As a somewhat male version for Phantasma, well... he's slow. But his immunity makes up for it like the old version of Voidknight)

Shai

-Increase in PvP damage

(She's not really that bad in arena, her SA rotations are actually good. She might just need a bit of damage since most of her skills are like damage over time unlike those one shot skills from other classes. But we won't really expect much since she's a support class. Maybe Shai is not just the choice of the majority)

-I suggest, having a MALE DISRUPTOR-TYPE CLASS with THE SAME RACE AS SHAI would somehow improve the love for Shai with a passive only exclusive for the two.

Mink would be a befitting name for the class, which means small and agile if you refer to a mink/ferret.

Think of an albino mink/ferret which has a control for both thunder and water. Like a Shai who controls wilderness and wind.

With the cuteness from both class it might just increase more Shai users and even pull in some new target players. 

Spiritwalker

- Reduce range for Dance of the Blue Dragon skill

(Even though she's a melee which uses a Bo Staff, why does this skill have more range than an actual range class Archer/Huntress/ Fletcher how come a Bo staff has more reach than an actual bow and arrow?)