After Natasha wounded Corvus Glaive in Avengers: Infinity War, she threw the spear to Proxima.
Was it accidental or intentional? If intentional, then for what purpose?
At least that's the way it appears....Proxima appears to call the spear to her so she can use it as a weapon.
It certainly looks, to me, as though it was pulled from Natasha's grasp rather than being thrown backwards.
There is a "transcript" at a Wikia (so not official) which would seem to confirm this that I am not alone in this impression...
[At the same time, Captain America throws Proxima's weapon to Natasha Romanoff (Black Widow) who engages Corvus, ducking under his swing, stabbing him in the gut and executing a flying kick to knock him backwards.]
[Proxima, who has rushed back to the fight, summons her weapon back to her hand and attacks Black Widow. Captain America leaps forward, rolls, scoops up Corvus's dropped glaive and holds her off.