Keen edge

Keen edge was a transmutation spell that doubled an edged weapon's threat range.

Effect
This spell made a weapon magically keen, improving its ability to deal telling blows. This transmutation doubled the threat range of the weapon. A normal threat range became 19-20. A threat range of 19-20 became 17-20. A threat range of 18-20 became 15-20. The spell could be cast only on piercing or slashing weapons (and it did not stack with itself). If cast on arrows or crossbow bolts, the keen edge on a particular projectile ended after one use, whether or not the missile struck its intended target.