Improved Critical

base attack bonus +8, Proficient with weapon,

When using the weapon you selected, your threat range is doubled. For example, a longsword usually threatens a critical hit on a roll of 19-20 (two numbers). If a character using a longsword has Improved Critical (longsword), the threat range becomes 17-20 (four numbers).

You can gain Improved Critical multiple times. The effects do not stack. Each time you take the feat, it applies to a new type of weapon. This effect doesn’t stack with any other effect that expands the threat range of a weapon (such as the keen edge spell). A fighter may select Improved Critical as one of his fighter bonus feats (see page 38).

Choose one type of weapon, such as longsword or greataxe. With that weapon, you know how to hit where it hurts.