http://wiki.project1999.com/Game_Mec...bat_and_Damage is a good place to start.
From the damage calcs listed there, you can see that the Silver Swiftblade will be able to hit the damage cap until 20, and it swings quickly on top of that. So it's an easy choice pre-20. After 20, the silver swiftblade is no longer approaching your damage cap, so it's a good time to look for a new weapon.