Complex sentence: He attained black belts in the martial arts Wu-Shu, Kenpo, and Go-Ju-Ryu by age 19, and he is proficient with the Filipino butterfly knife (Bali-Song).
Split into simpler sentences: He attained black belts in three martial arts by age 19 (Wu-Shu, Kenpo, and Go-Ju-Ryu). He is proficient with the Filipino butterfly knife (Bali-Song).