This is Starblight, a cursed cosmic sword from a Sentinels of the Multiverse role-playing game session (Sentinels of the Multiverse is copyright Greater Than Games, and both the character and the sword called Starblight were created by Adam Rebottaro). Included are both the original 'cursed' form of the sword, as well as the version created after the curse was removed by Stella Nova (renamed "Knight of the Stars").