I’ve seen more confusion than solid information regarding this topic, so I thought I’d share what my friends and I have reasoned out through some testing on our server. Every weapon and shield in the game has a stat value for Block Power, Parry Force, and Parry Bonus. This includes your fists, which have 4 Block Power, 0 Parry force, and a x2 Parry Bonus.
This is the base amount of damage your weapon or shield will negate while blocking normally, modified by your “Blocking” Skill. The true value is noted in the yellow parentheses. If a damage roll against your block exceeds the true block value, the attack will break your block and the residual damage will go through, modified by your armor and resistances.
Parrying an enemy is done by blocking just before the attack would hit you. The Parry Force determines how far enemies will be knocked away from you after a successful parry. A Parry Force of 0 will not knock back an enemy, while a Parry Force of 50 would knock an enemy back a substantial distance.
This is where these stats get interesting, and it involves some simple math. The Parry Bonus modifies your Block Power, and is what helps determine if a parry will stagger the enemy, allowing you to capitalize on the bonus damage. If a parry is successful, the damage you block is calculated by multiplying the Block Power of your weapon or shield by its Parry Bonus. If the final value is larger than the damage roll of the attack you are parrying, the parry will stagger the enemy. A Staggered enemy will take double damage from attacks. If the final parry value is less than the damage being dealt, your parry will be broken, the enemy will not stagger, and the remaining damage will be dealt, modified by your armor and resistances. It’s worth noting that even if the parry breaks, you will still negate more damage by parrying than standard blocking, so it is always worth parrying an attack if you can. The Parry Bonus of a weapon does not modify the damage dealt to an enemy staggered by a parry, only the Block Power of that weapon.
Example: You are wielding a Fang Spear, with a Block Power of 10, a Parry Force of 0, and a Parry Bonus of x2. You block a hit that would deal 20 damage. Your Block Power negates 10 damage, and you take 10 damage before armor and resistances. You then parry an attack that would do 18 damage. Your Block Power is multiplied by your Parry Bonus, for a total Block Value of 20, negating all the damage and staggering your enemy, which isn’t knocked back because the spear has 0 Parry Force. You try to parry a third attack, which rolls higher for damage, for a total of 22. You parry successfully, but only manage to block 20 damage again. Your enemy is unaffected by the parry and you receive a total of 2 damage before armor and resistances.
TLDR; Block Power determines damage negated during a block, Parry Force knocks back enemies staggered by a parry, and Parry Bonus makes successful parries block more damage, but does not affect the damage you deal.