Complex sentence: Manniche returned to Copenhagen in 1996, as an assistant manager; after a string of poor results for the club, he made a short comeback as a player, at the age of 37, calling it quits shortly after.
Split into simpler sentences: Manniche returned to Copenhagen in 1996, as an assistant manager. After a string of poor results for the club he made a short comeback as a player, at the age of 37, calling it quits shortly after.