It took six angels to cart away a human lost soul spirit. Why did it take six to do the job?

This was again not a physical commandeering of the spirit so much as creating an aggregate of energy that would be sufficient to entice him and his cooperation. Again, it was the demonstration of what he himself was lacking and the promise to bestow it that made the difference. So in effect, the cooperation of a group of angels in concert was needed to provide an effective show of strength, not of force, but of the powerful energy they command not only individually but collectively, and this became an enticement worthy of his cooperation and that was achieved.