Quill of Echidna

A quill taken from a slain demigod. Said to be sharp enough to pierce the very fabric of reality, yet more fragile than glass. Only three are known to remain. Amplifies magic cast through it, or can be used as a powerful spear.   One of the three is in possession of Kriv Turunroth, hero of the Sky Crisis.
Another is in possession of a warlock who defeated Certus Amphibole, wandering the continent searching for his missing half.
The third was used in an instrument owned by Melinda the Confusing, however the location of her weapon has faded into mystery. The weapon was found recently within Spear End, by Captain Cave Johnson.   Does 1d20 Piercing damage if used as a spear, or gives +5 to hit and +5 damage to spell attacks if used as a spellcasting focus, but not spells with saving throws. Shatters if a nat 1 is rolled, the shards dealing 2d20 Piercing damage to wielder and anyone within 5ft of the Quill. Cannot be mended by any means, magical or otherwise.