Schism Shard Crafting

You can craft Schism Shards acquired from the raid Killing Time with certain epic-level weapons to receive an upgraded or altered legendary weapon. Schism Shards are, and the crafted weapons are.

Crafting NPC
Varron Tertius 


 * Located in The Gatekeepers' Grove.
 * You have to complete Killing Time to speak with Varron and view the crafting recipes.

Ingredients

 * - found in the end chest of Killing Time as a rare drop. They are also available in exchange for 500 Time Runes. (Source: )

Base Weapons
Unlike most crafting systems, the base weapons capable of being upgraded exist across three entirely different quests from separate adventure packs:
 * White Plume Mountain
 * - Great Sword
 * - Quarterstaff
 * - War Hammer
 * Desire in the Dark
 * - Bastard Sword
 * - Great Sword
 * The Temple of Elemental Evil
 * - Scimitar

Sentient Jewels
Each of the recipes to upgrade or alter the White Plume Mountain weapons also requires that weapon's respective sentient jewel.

Upgrading Weapons

 * Base weapons must not have ever had sentient jewels slotted into them. In order to use such a base weapon, the jewel must first be removed or destroyed. After you have unslotted the sentient jewel, selecting the upgrade target weapon in the forge window will show the base weapon as "This weapon must not be sentient", and won't accept it. Instead, the base weapon must be dragged into the ingredient area of the forge window.
 * Additionally, sentient jewels used as ingredients for upgrading must have 0 Sentience XP.
 * Note that with the White Plume Mountain weapons, each has an option of either a direct upgrade to the weapon, or an upgrade to a secondary weapon type. Be careful when making your selection!

WARNING: Any Mythic or Reaper bonuses the base weapon has will be lost on upgrade.
 * As of Update 41, players will be able to spend a new raid ingredient,, to add Mythic +2 or Mythic +4 bonuses to the upgraded versions of these weapons. (Source: )