The Strength attribute increases the damage you do in
Formula: +1 dmg = x/10 points
For each level you get 5 attribute points, so that would mean 1 damage increase for every two levels, if you invest them all in strength.
Recommendation: It is currently recommended to start with strength first 12 levels because of the Blacksmith damage upgrades.
12 levels worth of attribute points mean 60 points in strength, meaning +100% possible damage with blacksmith upgrades (done with ingame money).
The Claws weapon for level 12 does 18 - 25 dmg by itself. The Claws +4 (4 dmg upgrades at the blacksmith) mean 36 to 50 dmg. +6 dmg from the str bonus = 42 to 56 dmg.
That means you are killing mobs 2.33 times faster.
* XP Boost * Gold Boost * Criticals * Reaping * Salvaging * Strength * Lumber Boost * Mine Boost * Defense * Scavenging * Taming