She was only given the opportunity to cast a spell like that because Droma was emotionally compromised and not attempting combat, while Nomi drew heavily on her anguish to so completely sever him.
I doubt she'll be able to spawn a Wall of Light at the same time as fending off an attacker unless an opportunity is created. It's almost like my stance on Zannah's illusions, but even moreso in this scenario.
Originally posted by NewGuy01
That clearly wasn't a wall of light, that was a Force Push.
"He reaches deep into the light, drawing on the bright power - As he tried to teach Nomi Sunrider."
Yeah, sounds like a Force Push. :I
For reference, this is right after he'd taught Nomi the Wall of Light technique. It's basically undeniable that he used Wall of Light.