Character stats play an important role in the game. Each stat is a little different than the MMORPG version.
Strength: The Strength stat increases the maximum physical damage that characters can deal with basic physical attacks and combos. At 30 STR, a character will do twice as much as damage than at 1 STR. Strength plays a predominant role in the Swordsman and Merchant classes. It also helps Acolytes who use special ro moves and normal attacks as their main offense, as well as allows thieves to do more damage per hits. Arrow damage, however, is not affected by STR.
Agility: The Agility stat increase the character evasion and speed, including cast speed for Magicians and Acolytes as opposed to Ragnarok Online, in which DEX determined casting speed. Many of the classes require 10 to 20 AGI to gain an A-button combo move. AGI is an important stat for Magicians due to their low HP and ragnarok zeny, but is not useless even for Novices and Merchants who are the slowest classes in the game.
Vitality: Vitality increases the character hit points, defense against physical damage, resistance against status ailments such as Poison, and hit stun. The Swordsman has skills which are augmented by VIT, such as HP Recovery, Endure and Moving HP Recovery. Any character who receives damage can make use of this stat or ro zeny.
Intelligence: intelligence raises the maximum SP, the damage dealt with spells by Magicians and Acolytes and spell defense. Also every 16 points of INT raises the potency of the Acolyte Heal spell. Intelligence also affects the rate at which SP recovers ro zeny, which is useful for any class who is going to rely on spamming skills as often as possible.
Dexterity: Dexterity increases the minimum damage dealt by the character. For Archers, DEX determines the maximum damage dealt by their arrow attacks as well. For every 10 points of DEX, the character can also chain another heavy attack into a combo.
Luck: Luck increases the critical hit rate by 2% for every 3 LUK. The game manual also says that LUK raises lucky, which is short for the term lucky dodge, much like the one on Ragnarok Zeny. With the exception of the female Merchant who needs 10 LUK to gain an A-button combo and ragnarok zeny move the LUK stat is not required for any special moves.
Another role of character stats is that each class has moves with stat requirements. These stat requirements must be fulfilled before the characters gain certain moves.