Meaning a solar eclipse when the moon passes between the sun and the earth. It is said in the Prophecy that when all three pieces of the E'Clipser are found a 'shadow will fall upon the world of men'. All three pieces together make a sacrificial knife that is used to make 'shadow' fall on Liveside so that Mike now The Shadow Man can fight and destroy The Five and collect all the Govi 's in Liveside also.

Eclipser (my screenshot)

The three pieces are:

  1. Le Soleil- Brother Sun
  2. La Lune- Sister Moon
  3. La Lame- The power that binds

So essentially Mama Nettie is controlling the lunar eclipse to make it night with her voodoo powers for a long period of time until Shadow Man rids the world of The Five to save the world. The three pieces aren't weapons and are just items in the game.