Thoughout the whole movie, Kaecilius and his minions never use any relics as weapons. They always conjure weapons instead.
Does that demonstrate that relics never get to choose zealots as their users, or they are just not user-friendly for zealots?
The only clue I have is what Mordo says in the middle of the movie:
This is a relic.
Some magic is too powerful to sustain...
so we imbue objects with it...
Not sure this is relevant.