This is another very build dependent thing about the Rapier. It can be very beneficial to have ability perks on it, or it can be more effective to have damage focused perks on it. For healers, it is best to use ability perks on your Rapier with critical hit modifiers. You could use either Refreshing Fleche or Sundering Riposte with Keen Speed and Keen. For builds with Bows and Muskets it is best to get additional cooldown reduction build in. With a Bow you can use Icicle to get another stack of Refreshing Evasion and two strong offensive perks. For Muskets you can use Sacred Woodsabre to get another stack of Refreshing. In PvE, focus on damage modifiers such as Vicious and Bane Perks. You will almost never use the Rapier for primary PvP damage, so it is better to have utility perks.