Our killer is also similarly dressed to Commissioner James Gordon from the Batman series who always appearing in darkly dressed clothing and weapon of choice, a gun. Our killer is a professional who will have knowledge on how not to get caught. Much like James Gordon he works alone and doesn't want other to pull him down. However, Gordon fights crime for a living while our killer creates destruction and appreciates people committing crime. Gordon is open about his appearance as he represents a heroic figure in Gotham City but our killer remain anonymous to remain a threat to all of those who walk in his path.
All the characters featured in this question are strong minded and are determined to fight issues that come in their way by weaponry. They also use their weapons for comfort because they also feel threatened by others that could assassinate them. They have the classical stereotype of testosterone poisoning believing the more masculine they appear, the more negative traits they would have.