IAS is an acronym for "increase(d) attack speed." This term generally refers to one of the many skills that increase attack speed.
Note that skills which claim "you attack x% faster" actually decrease the swing time by x%. For example, using Frenzy ("attack 33% faster") results in 50% more swings in the same time. Thus, it yields 50% more weapon damage, adrenaline gain, and bonus effects such as from vampiric/zealous weapons.
Related articles[]
- Increased Attack Speed and Decreased Attack Speed
- For a list of all skills that increase attack speed see attack speed skills quick reference.