Complex sentence: He has a thing for Norta but she is engaged to a Demon even more powerful than his brother, Fatalis, though after taking the Final Exam Dev seems stronger, though never gets the chance to show his skills.
Split into simpler sentences: He has a thing for Norta but she is engaged to a Demon even more powerful than his brother, Fatalis. After taking the Final Exam Dev becomes stronger, though never gets the chance to show his skills.