Complex sentence: The duties Marine warrant officers typically fulfill are those that would normally call for the authority of a commissioned officer, however, require an additional level of technical proficiency and practical experience that a commissioned officer would not have had the opportunity to achieve.
Split into simpler sentences: The duties Marine warrant officers typically fulfill are those that would normally call for the authority of a commissioned officer. However, they require an additional level of technical proficiency and practical experience that a commissioned officer would not have had the opportunity to achieve.