Strength:
Strength affects both the amount of damage you do as well as your chance of hitting an opponent.

Dexterity:
Dexterity adds to your AC, which increases your chance of blocking an attack.

Wisdom:
Wisdom is used to calculate how much experience you'll gain from a fight.

Constitution:
Constitution is related to the number of hit points you have.

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Attack:
Increases chances in a fight while using a weapon. Also used to determine what weapons your character can equip.

Defense: Increases chances of defending yourself in a fight. Also used to determine what armor your character can equip.

Weaponless:
Increases chances in a fight while not using a weapon.

Lockpicking:
Increases chances of unlocking a door.

Disarm Traps:
Increases chances of disarming a trap.