Why are you using 45 dex? Are you going to use Pyros? If you aren't using magic/miracles/pyros, then keep don't go above 40 Dex. Your AR won't uncrease more than a point or two. The only reason to go to 45 is to increase your spell casting speed (which caps at 45).
i used a bss with no buffs and 40 dex its decent but not the best. well its probably the best straight sword unbuffed dmg wise besides sunlight ss,but you need 40str&40dex so balder ss is better imo. black knights are a good enemy to test weapons on to see how much dmg you will get in pvp. you have to remember that you could get better or worse dmg depending on their armor. you should really have some resins or a buff for when you run into really heavily armored players.