When I lived in Dublin and London I carried a shit load of keys like that and when I was walking alone at night I kept them bunched up in my right hand, the longest keys between my knuckles, so I could throw a painful, bloodletting punch before running away (should the need arise). Luckily it never did.
Here in France I can legally carry pepper spray, so I do. And a knife. :smile:
Disclaimer: I know how to punch without breaking my hand and how to fight with a knife - those that don't should stick with pepper spray and rape alarms, and should also take self-defense lessons.