What Lenny said, and here's how that's different from other abilities.
If you want to make a 2H warrior for instance, you can invest in 2-Handed weapons, which says if gives 5% more damage, or Warfare, which also says it gives 5% more damage. But Warfare works differently to every other +5% damage ability.
2-Handed takes your base damage, let's say it's at 150%, and adds 5%, so 155%.
Warfare takes your base damage, let's say it's at 150%, and multiplies it by 5%, giving you 157.5%
That's why Warfare gives you extra damage.
