There are various ranges (randomness) for attacks. I'll try to not get too boringly technical.
- Hit chances are random.
- Damage Ranges are random. Each weapon has a random range, and damage potential goes in steps until you reach the best for that weapon.
- Critical Hits are random. Similar to Damage Ranges, but you need to land a exceptional hit to have a chance to score extra damage. All weapons have different critical hit chances and damage ranges.
- Resistance Ranges are random. Similar to Damage Ranges above but involves armor, helmets, and belts instead of weapons.
- Exceptional Damage Resisting is random. Think of it as critical hits, but for armor.
- Attacking first or second, what we call Initiative, is random. In each pair of attacks we determine who goes first.
Your chances to do something are not based on your raw abilities. They are based on who you are fighting. You will see more of a range against someone you are close in strength with. Your level, stats, equipment, and your opponent are all variables in the combat equation, along with your gang bonus, attack type, encumbrance, etc.