Complex sentence: In Omen of the Stars, she becomes a warrior because she revealed that she had kits (Hollyleaf, Jayfeather and Lionblaze), however, Jayfeather views her as being incompetent as a warrior.
Split into simpler sentences: In Omen of the Stars, she becomes a warrior because she revealed that she had kits. However, Jayfeather views her as being incompetent as a warrior.