The Space Shards were mystical constructs manifested by the Zealots to be used as weapons. They massively used them during their attacks on the different Sanctums. One Master of the Mystic Arts was stabbed in the back by a Space Shard while attempting to flee to Kamar-Taj.
Kaecilius and two other Zealots used Space Shards during the Battle at the New York Sanctum. Daniel Drumm was killed after Kaecilius stabbed him twice with a Space Shard. Kaecilius and his Zealots then attacked Doctor Strange with their Space Shards, although he was able to parry most of his attacks with his Eldritch Whips. The Cloak of Levitation also protected Strange from being stabbed by a Kaecilius armed with a Space Shard. Eventually, Strange was heavily wounded by a Space Shard thrown to him by Lucian Aster, forcing him to retreat to Metro-General Hospital to be healed by Christine Palmer.
Back to the New York Sanctum, the battle between the Zealots and the Masters of the Mystic Arts was resumed, with the Zealots once again massively using Space Shards to attack their enemies, including the Ancient One. Using her Tao Mandalas and her mastery of martial arts, the Ancient One was able to repel her opponents, but ended up fatally stabbed by a Space Shard wielded by Kaecilius, who pierced through one of his Zealots to reach her.
Kaecilius and his Zealots manifested Space Shards when attacking the Hong Kong Sanctum, with Wong being one of the victims, although he was later resurrected when Strange reversed time. Kaecilius attempted to strike Strange with a Space Shard before he could activate the time reversing spell, but failed as his weapon stopped right in front of Strange's face.