The Angelic Shard drops from Izual in Act IV, and the Blacksmith will use this item to craft the Hallowed set. The Angelic Shard also drops from Corrupted Angels which you will probably find often in the Silver Spire Level 1 while completing bounties in your group, but it is more effective and less time consuming to farm Izual solo several times until it drops.
Source
Drops from: | Act | Location | Portal | Image |
Izual | Act IV | The Great Span | The Silver Spire Level 1 | |
Corrupted Angel | Act IV | The Silver Spire Level 1 | The Silver Spire Level 1 |