Gotta disagree with those who suggested knives. How big is she? How much training has she had? How aggressive is she? Do you really want her in close enough to a criminal to use a knife?
She's pretty small, has no training, and is looking for something short of a gun. Does anyone have a specific pepper spray product to recommend, or does it not really matter, just buy anything?
A certificate for a course like this one:
Insights Training Centre Unarmed Self Defense http://www.insightstraining.com/ps/courses/unarm/usd.htm or from Demi Barbito http://www.demibarbito.com/ plus a can of FOX OC spray and a SureFire E2e tactical flaslight (60 lumens blinding power buy time for evasive movements or buy time to spray).
Walt Marshall has classes at Reeds in Santa Clara as well as East Bay.
I believe that Walt has specific 2-day edged weapons defensive classes for women. Highly recommend you take a few of their gun tactics classes as well. Walt is a friend of John Jardine -maker of that Valtro you're packin'.
Take a look at their site, the trainers are real fighters who have survived multiple street encounters. Not just martial artists working with theoreticals.
btw. Did I mention that Walt consults for movies, like the bank robbery scene in "Heat"?
Hate to sound like I'm jumping on a band wagon but...Training.
Find something that stresses preventative measures and situational awareness. These courses tend to fall under ideas like "safe business traveler" or "self protection for the executive". They may get into some stun-and-run tactics but it's mostly mind set and prevention.
If she's interested in a continuing education in self defense, maybe the two of you could sign-up for Krav Maga or some other combative together for the new year.
Actually, though I've done quite a bit of 'instruction' with her and guns, I'm going to look into training with Walt here in the Bay Area for her _and_ I.
Now, on the pepper spray stuff... Fox makes so many units... which to choose?
I got the women in my life the Foxlabs 2 oz. Medium Fog Cop Top type. Good size for the purse, good positive firing system, small size but bigger then their keychain units.