When he said 'Ben', Jaina felt her stomach tighten a bit. As he added his last name, her stomach dropped clear to her toes... and her jaw very nearly did the same. Her eyes widened as well, to very nearly comical proportions. In fact, if Jacen were around, she likely would never live the expression down. However, in her state of shock, she didn't even realize she was making such a face. She was simply too stunned to even think properly.
When he mentioned her lightsaber, however, Jaina managed to drag herself out of her stupor. "You're..." She stopped, clearing her throat a bit. "You're Obi-Wan Kenobi! I knew I recognized you!"
Realizing she wasn't sounding quite her tender age of thirty and really was more resembling a small youngling at the moment, Jaina drew in a breath and tried to calm herself. It worked, externally at least, although inside she was still stuck somewhere in reverence and awe.
"I've grown up learning about you. My uncle and mother..." Then she stopped, suddenly, as she realized he'd have no idea what she was talking about. Deciding to try again, Jaina offered a simple, "I'm the daughter of Leia Organa. Luke Skywalker is my uncle. Half of what I know, I learned from him. He learned at least part of it from you..."
She left it at that, not wanting to throw too much at him (and never thinking she might have already done so with just those few simple sentences).