The Comb is an item in Shadow of Memories.
'An antique Comb. A precious gift from Margarete.'
Eike will receive the Comb in Chapter 5 after returning home with Margarete. Despite your choice in this moment Eike will receive the comb as a gift from Margarete.
The comb is automatically used in a cutscene during Chapter 7 when Eike confronts Eckart Brum.