Every night before 27-year-old Arin goes to bed, she hangs her Makarov, a Russian semi-automatic pistol, from a steel coat rack by the entrance to her one-bedroom apartment in a small, dusty town on the Syrian border with Iraq. The pistol was an award for her success on the front line in the battle to protect Kurdish areas of northeastern Syria and is a far cry from her life a year ago when she was working as a nurse in Cologne in Germany.