Some decent fighting moves would be very helpful. I may have been too quick to dismiss the sonic blast power of alarms but OTOH, if someone is hopped up on adrenaline (or more powerfull pharmaceuticals) The impact may not be what it is on someone just curiously trying out the device. Most attackers are somewhat agitated when the event starts unless they are the truely cold-blooded. In either case the level of adrenaline or cold-bloodedness will be a defense against many things that aren't truely painful or injurious.

Carrying you keys protruding between your fingers, hand closed as a fist around a small Kubaton in the palm is something you could certainly get away with in areas where weapons are banned. If you are concerned about the Kubaton then get a mini-mag or mag-solitaire to put on your keychain. With this "enhanced" fist you can inflict a lot of pain if you strike flesh anywhere on your assailant. That kind of pain and true injury will buy you some time also. The combination of the surprise of the alarm to buy enough time to land a direct blow to the cheek / eye area of the head with the enhanced fist should get you a few seconds to run and also make the assailant somewhat less likely to follow. If you can learn a few moves to break a hold and a couple of kicks for knees and groin you will be much more capable. This isn't a lot of training - you could learn to break holds in a week at the outside. Kicking in such a way as to not have your foot traped by the assailant is a bit tougher. Slamming a fist full of keys into someones face shouldn't take much training at all, just readiness to do it.

I find that if I feal threatened I immediately start thinking of ways to do harm to the threatening individual. The fact that my thoughts are occupied with hurting them shows in my body language and they usually leave me alone. May sound savage but it is just the savageness in others that I am attempting to deflect.