-Firepower determines how hard your weapon can hit. In simple language how high the damage output can be. We count damage in hit points. Firepower of 300 means that the maximum damage can be 300 hit points.
-Accuracy determines how accurate your weapon can fire. In short, it determines the scale of the firepower finally dealt. A highly accurate weapon is more likely to output shots close to its maximum firepower while a weapon with low accuracy will more likely output low percentage of the weapons firepower.
Of course, how good one shoots does not only have to do with weapon statistics. It also has to do with character attributes.
For each round of battle, a die is rolled. The die is affected by character morale and luck. Once rolled, this is where the accuracy skill kicks in. Accuracy skill will determine in dependence of the roll the percentage of damage finally fired by the character. Do take in mind that the weapon damage output is also affected by composure. A very lucky character that does not have accuracy skill will still fire worse than someone with the accuracy skill who is not as lucky. Lastly, accuracy skill points are first calculated based on strength. So without strength, you won't utilize the skill at its maximum.
Once the blow is fired, the defender will either reduce the blow with its armor, or dodge it with dodge skill. Armor is solely decided by the armor value of the armor the character wears. The dodge skill works also with a dice while dexterity plays an important role.
Quick Fire skill allows the character who has it to attack 2 times in the same round. This won't happen always while a die is also rolled for this. Dexterity plays an important role.
Finally, the character with the highest dexterity fires first each round. If the two contestants have similar dexterity, a die decides who will fight first each round.