Thought I'd post this here to help out. There are a lot of (somewhat unexplained) stat interactions in the game, the biggest being all the stats that combine for physical damage.

Physical Damage

The stats which affect physical damage are:

• W. ATT
• Agility
• Job Level
• Accuracy
• Crit Rate
• (Related support abilities, special weapon effects and buffs)

W.ATT is fairly simple. The more you have, the higher the base damage of your attacks. Crit Rate is also as expected. The effects of the remaining stats on damage are the less intuitive ones.

When your character uses a conventional attack, you'll notice soon into the game that they can attack and hit multiple times. The amount of times the character will attempt to attack is determined by that character's agility and job level (if you're having trouble dealing enough damage in a boss fight and recently switched classes, switch back and see if you deal more damage by hitting more). The number of attempted attacks is capped at 16; the Ninja class's final ability increases the cap to 32; it requires a very specific build/buffs to reach 32 hits per attack, however.

Accuracy comes in here: Each attempted attack can miss. The higher your accuracy, the more often each hit will connect. This raises your average damage within your potential damage range.

Finally, what ties this all together: Most special physical attacks state they deal damage based on "x% of the damage of a conventional attack". Special attacks calculate a full basic attack before applying that multiplier - in other words, all physical attacks, even those that only appear to hit once, still rely on Agility, Job Level and Accuracy boosting your hit count.

The end result is that agility-based classes such as Thief, Ninja and Ranger do as well in a physical role as strength-based classes such as Knight, Swordmaster and Monk; it also helps show that Agility equipment such as the Hermes Shoes and Red Cap can be potent for increasing damage output. Slower, stronger classes will benefit more from agility equipment as it will increase their number of hits by a greater %, and each hit has a higher damage with higher W.ATT.

On physical classes, "optimum" equipment will only consider the final W.ATT/W.DEF the gear gives you; it will not consider the potential benefits of using gear with a higher crit rate, accuracy or agility bonus

Magical Damage

Magical damage comes purely from M.ATT, which is derived from INT. Raising job levels will get you access to spells with higher base damage and passives which affect magic attacks.

It should be noted that the penalty for dual-wielding is that each hand's total W.ATT is halved. As magic deals damage based on M.ATT, this is not a penalty for mages - they get the full M.ATT of each Rod when dual-wielding

Magic-based Healing

Healing white magic scales off Mind. It should be noted that White Mage-type staffs increase Mind, but not M.ATT, and White Mages have a lower M.ATT than other mage types, but all mages still have a decent Mind. Quite often you can make any mage use White Magic as secondary and be effective, while being able to deal more damage with Black Magic (or White Magic's Aero spells)

Turn Order

Turn order is based on Speed, which is derived from Agility, %speed support skills (Thief has them) and %speed buffs in-combat. Each turn, the game randomly multiplies each character's speed to get a value used to determine which character goes first.

The thing to note here is that in my experience, a character with 30% more speed than another character will always go before that character. So for example, if your fastest characters are the same job, you can make sure one of them always goes first by equipping Speed 10% and Speed 20% from the Thief class. This can be very useful for Mimic-based setups by the end of the game, as you'll be able to set up knowing which character will go first.