Fatality might not work with bows, but Ranged characters have something similar with Death Blow, which DOES work with Bows and it increases the chance of doing critical hits. Since rangers put lots into Dexterity, which is used by Heightened Reflexes to increase the damage of critical hits, you can see how that would be helpful. My ranger near the end of DKS was at 62% chance to perform a critical hit, which did thousands of damage with my bow.
