I'm going to interpret this as "Four things to always have on your person in addition to typical daily ballast". Typical daily ballast is what most people have on them: watch, wallet, keys, and cell phone.

1) Flashlight - No working streetlight and the glare from passing cars kills your night vision. Not to mention most bathrooms don't have emergency lighting. You haven't lived until the lights go out while you're on the john.
2) SAK or MT - Being able to cut things is good, but a knife isn't a screwdriver or a bottle opener. Urban setting means more mechanization. Carry the correct tools for it.
3) Whistle or alarm - No argument. It's better than screaming and makes for cool keychain bling.
4) Pen and pad - Don't count on decent recall when you're stressed or tired. Remember all those history tests you blanked on? If it's important; write it down.

EDIT

As far as the no-knife workplaces: How do they feel about bladeless/scissors only multitools? Will they accept it on the technicality that there are no cutting edges or piercing points, or is it a blanket ban on personal tools?