Complex sentence: Naraku then reveals that the reason he created Akago as an infant and purposely made him so weak, while providing him with a powerful barrier that he had the power to disable, was because he always knew his heart would turn against him.
Split into simpler sentences: Naraku then reveals that the reason he created Akago as an infant was to purposely make him weak. The reason he provided Akago with a powerful barrier that he had the power to disable, was because he always knew his heart would turn against him.