I don't think this was Derek Condon's first rodeo, thank heaven it was his last. Pistol whipping and handcuffing elderly women in his past home invasions no doubt negated any feeble resistance they might have offered. The presence of a home defense handgun made all the difference in this instance.
On another forum, a member speculated that he may have handcuffed one of her hands to the chair arm and was confident that would keep her more or less immobilized. If this was the case, she could have used her free hand to retrieve and fire her revolver.
Obviously, as she fired at him, he was returning fire. She took multiple hits. It is entirely possible she was knocked out of the fight before she could empty her revolver.
A lot of speculation here, but these stories always lack detail.
I'll be waiting for "Fair and Balanced" NPR to report this story.