When you will be AOEing mass mobs in 12Sky. It all really depends on what you feel will work with your skills/weapon.

Light Blade
Ive noticed because of the skill Steel wall (which adds to defence%) killing is alot easier with a light blade jinong because they take alot less damage, thus meaning you are able to pull more mobs to AOE at once.

Because of Steel wall you wont have to invest many points into vitality

You will want chi very early since it will take a bit longer to kill because of the lack of damage compared to a long spear.
-13-15 chi total before level 15.

-The rest should be focused on dexterity and strength. Depending on the monster you are fighting you will end up rotating between 3dex 2strg or 2dex 2strg 1vita

-Defence is a must while a long spear is taking 50-60 damage per hit you will only be taking 1-20

-1 point in the AOE skill Bloody Whirlpool should be enough until 25+
-Make sure to max Steel wall to decrease enemy damage as much as possible.
-You will kill a bit slower than a long spear jinong but your survivability is extremely high.

Long Spear
Long spear jinong will have the upperhand in killing faster but since your defence will be lower than a light blade jinong, you will end up using potions very quickly. And with the cost of potions it can get pretty expensive if you are killing recklessly or killing mobs too high of a level.

-1 point in Banshees cry should also be enough till 25+
-Will need more health than light blade jinong.
-Same goes for chi as a light blade jinong, make sure you have enough so that you dont run out during your AOE attacks unless you will be using CHi potions.

-Mindless Rage is a must to max because of the extra % to damage. Up to 20%

-Again you will be switching between strg and dex its up to you.

-and you will be using lots and lots of potions!

Finally,I want to recommend you to buy 12sky gold from us.