الْمُوَكَّلِ بِقَبْضِ أَرْوَاحِ الْعَالَمِينَ
Entrusted with taking the souls of the worlds.
Muwakkal means one who has been assigned a task. The description shows that the Angel of Death is a commissioned servant; other angels assist in this assigned work.
وَهُمْ لَا يُفَرِّطُونَ
And they do not neglect their duty.
The expression emphasizes obedience and precision in carrying out the assignment to take souls.