Complex sentence: In addition to being a strategist, Yú was also a martial artist who specialized in the weapon art "Jingchu Changjian" and compiled the martial arts manual, entitled "Jianjing" ("Sword Classic").
Split into simpler sentences: In addition to being a strategist, Yú was also a martial artist who specialized in a style of weapon fighting called "Jingchu Changjian". Additionally, he compiled a martial arts manual entitled "Jianjing" ("Sword Classic").