Complex sentence: In one episode Charlie was training in weapons and tactics in LA's FBI school, where he showed to have a high skill in marksmenship at the range, impressing many of his FBI training peers as well as his instructor.
Split into simpler sentences: In one episode Charlie was training in weapons and tactics in LA's FBI school. Where he showed to have a high skill in marksmenship at the range, impressing many of his FBI training peers as well as his instructor.