Boosts certain Skills like Permafrost and frost explosions - See Frost/burn listed as a damage type on a skill? This boosts it, every axe attack when charged with permafrost, as well as those skills that say 'explosion of frost' etc. Boosts Runic Attacks - Working similarly to strength, you need to outclass the enemy's defense stat with your runic to deal ever more damage. Doesn't Boost Atreus - Only his weapons, gear, and skills boost his damage. Regular Draugr have low defense, but enemies like Travelers and Valkyries have much more. Enemies have defense - boost strength well beyond the enemy's defense (an unknown) to deal the full potential of your damage. Boosts physical damage - not runic attacks, but all fist, shield, and weapon attacks. Permafrost effects are boosted by the Runic stat. The Six Stats of God of War Strength boosts all physical damage, including ranged. Follow the links below to read more about each stat (it is all on one separate page but the links will put you in that section). I'll go a bit deeper for those who care to read.
So, with all these different stats and all they do for you, how do we put them together to make a good build? This guide will summarize what I learned about the strength, runic, defense, luck, vitality and cooldown stats. How to Make a Build for Kratos Using What We Know about Stats in God of War