When using swords, grants Crit.Dmg +10%. When refining is +5 and using swords, grants Atk +2%, Crit.Dmg +2%. When refining is +10 and using swords, grants Atk +3%, Crit.Dmg +3%. When refining is +15 and using swords, grants Atk +5%, Crit.Dmg +5%.
Starting from refined +8, every +1 refining increases Atk & Crit.Dmg by 1% (up to 8%).