What do the four primary stats do in this?

[Rather Useless]

I think they're, strength, speed, resistance, and intelligence? Like, I'd saved up a bunch of strength tabs, then used them all at once to see how noticeable the effect would be, and it didn't seem like they increased physical damage inflicted at all, but maybe that's not what strength does in this game. So, I'd like things clarified is all.

[BlackRaider2012]

more strength, increase your melee damage and its critical chance, you don't see its effect in the character ATK stat itself. Its like when you attack your final damage will be (ATK+strength % value or something similar), it shows in the damage number that appears when you do a successfull melee attack on an enemy. This is most noticeable with strong animals and strong melee based characters. I don't know if strength, helps to resist melee attacks (together with PDEF), though. This isn't so obvious to see.

more speed, obviously makes you have your character turn faster then the enemy. The more faster you are, the better, obviusly if you attack first, you can kill first and faster. This works mainly on melee attack speed. I don't know if this applies when you use pure spells instead of melee or special melee attacks. Oh, more speed makes enemies fail more melee attacks against you too.

non melee spells never fail their target so, resistance helps in this part, together with MDEF. Making you lose less and less HP until you lose 0 HP, the equivalent to a miss on a melee attack. This stat makes more dificult to gain bad status conditions too, like disease, poison and all others. If you don't have any item to make you immune to a element or status, resistance is the main stat to defend against it.

intelligence increase the efficiency and damage of your non melee spells and their critical chances. your final spell damage value will be a % of you spell default damage value + a % of the INT value your character have.

Note: don't forget enemies have defence against spells and melee too. If you increase your strength by 100 or 200 but your melee damage doesn't increase much, then you need to change strategy by using spells.