Complex sentence: Yuno could only admire how Asta saved him, despite not having magic, and it made him feel ashamed and to make up, he trained himself to become his equal, in a moral sense.
Split into simpler sentences: Yuno could only admire how Asta saved him, despite not having magic, and it made him feel ashamed. To make up for this, he trained himself to become Asta's equal, in a moral sense.