
Simply wielding the weapon will raise your Item Discovery stat, making it great for farming.
The Crystal Sage's Rapier is a special weapon transposed from the Soul of the Crystal Sage, which can be gained early on in the game. Because of this, you'll only want to equip this when you have a farming spot close to a bonfire - or at least pack lots of Estus. This helm boosts your Item Discovery Rate - but at the cost of constantly draining health.
Every Mimic you meet has a chance to drop it, but the last Mimic left in the game should drop it regardless - if you haven't found it before then.
The Symbol of Avarice is a funny looking Mimic Hat that is dropped from killing a random Mimic in the game. Dodge it or kill it, and look around its lair for a body holding the shield. Take a detour down the bridge before High Lord Wolnir to enter the Smouldering Lake, and head left to where a Giant Sand Wurm has made its home. The Shield of Want is a special magical shield that allows you to obtain more souls from enemies, much like the Covetous Silver Serpent Ring - though it's located about halfway through the game. At the roof of the shrine, look for an open window along the far wall you can jump into that leads to the Old Cell where the ring is located. First you must find the Old Cell Key in a chest in the sewers beyond the Giant's Cell, then head into the Profaned Capital before doubling back to the dungeon through a side passage until you come to a large shrine amid a poisonous lake. This ring can be found deep in Irithyll Dungeon, in a cell with a window looking into the Giant's cell. The Covetous Gold Serpent Ring increases your Discovery stat, making you more likely to find good items when killing enemies. Skip the Key - Find out how to glitch onto roof of Firelink Shrine