Has she spent any real time with a small revolver before?
I've got a S&W 640 that's my "I'm too lazy to dress for my gun so I'll shove it in a pocket" EDC. Steel frame and everything. I'm probably a lot bigger than your wife, maybe stronger, and when I practice with it with NON-+p rounds it's punishing on my hand and wrist.
Not a big fan of small revolvers for less-than-experienced shooters.
ETA: I should have read the thread. But I'll stand by my answer even if everybody else agrees and that conflicts with my contrarian streak. Besides, a smaller striker-fired pistol (Glock 26 or the new .380 Glock, or S&W M&P9 compact) is every bit as foolproof as a revolver (if not more so, what with having probably a much better trigger), and less punishing. Besides, if it's a CCW then the chamber should really never be empty. People with far more training than you, me, or her will already be behind the power curve in an intense inter-personal conflict, and having to fight to get a gun into action won't help matters at all.