This skill upgrades a character’s Slay skills so that they will inflict additional damage. For each purchase of Improved Slay, each of a character’s Slays will add an extra five times the weapon’s base damage.
For example: Barinor has two Slay skills. With his long sword, he does 20 damage with each Slay. He purchases a single Improved Slay skill. Now his Slay damage is set at 30. With a second purchase of Improved Slay his Slay damage goes up to 40.