Crystal Sage's Rapier

The Crystal Sage's Rapier is obtained by transposing the Soul of a Crystal Sage. In order to acquire the rapier, you must first defeat the Curse-Rotted Greatwood and obtain the Transposing Kiln. Give the Transposing Kiln to Ludleth. Then defeat the Crystal Sage. Equipping the rapier in either hand adds 50 points to your Item Discovery. Upgrading the rapier does not increase your Item Discovery.

In NG+0, an effective strategy against the Curse-Rotted Greatwood is to equip a Raw infused Broadsword+3, buff the weapon with Charcoal Pine Resin/Bundle, and spam R1 at the egg sacs. For the Crystal Sage fight, equip pieces of armour having high magic defense, buff a Raw infused Broadsword+3 with Charcoal Pine Resin/Bundle, consume a Blue Bug Pellet, and spam R1 at the Sage who fires purple (as opposed to blue) magic. If you want, use the Blessed Red and White Shield+1 to block magic and/or Summon Eygon of Carim. In the second phase of the fight, multiple copies of the Sage would spawn. There are 2 easy ways to tell which is the real Sage. First, the copy that uses purple magic is the real Crystal Sage. Second, use a Throwing Knife against any copy. If the Sage is killed in one hit, then that copy is fake.