Either he materializes MX's keyblade out or picking up kairi's keyblade in two seconds off screen before he hands it to her after the flash of light but he didn't summon his own keyblade to knock out a bunch of heartless that covered Kairi.
I personally believe that Kairi's keyblade was shown in her hand offscreen then unawarely dropping hers when she was pulled up on stand by Riku after the flash.
It seems like that she materialized it herself but is unable to do it afterwards until she had began training under yen sid to summon hers in KH3D secret ending.