This is admittedly somewhat hard to test, but I THINK the following is occurring.
1) I throw Mirror Blade
2) I become Blinded (screen goes dark around the edges)
3) Mirror Blade reaches the target
4) No damage is done, no clone spawns
5) Blind is still active (screen is still dark around the edges)
6) Spacial Surge fires
7) Blind is removed (dark edges disappear)
If anyone else can confirm, that would be great. I was fighting some of the risen outside of the Rally Waypoint in Malchor’s Leap when I noticed this.
edit – To clarify, Mirror Blade does not cause me to become blind, the issue seems to be when I receive a blind while mirror blade is in flight.