The little Glock M-26 would be a good choice.The problem with the SIG 357 is the recoil might be to much for her and the ammo is quite pricey. I might suggest a Glock M-27 . That's a 40 cal. The recoil isn't real bad and it has allot more punch for a SD gun.I had a G-26 and traded it off when I finally got my G-27. They were scarce when they were first released.Onanother thought if your wife isn't real experienced with guns Imight suggest a small framed revolver in 38spl.They are pretty much fool proof and better suited for a new shooter.