Kind of debating whether or not she had enough strength to even demonstrate now. Trying to force the Radiance to work was usually...tiring. And of course she's tried countless times once she was told about it. Give any kid a superpower and you bet they will look for every way possible to use it.

"It usually doesn't work," as Puella speaks, she forced the Radiance again. The Flame was too small, too weak, like trying to light a bonfire with a single ember. A faint, orangeish light pulsated from her chest for a few seconds, but once she had to stop holding her breath, it snuffed itself out.

Puella could have maybe held it for a bit longer, but she didn't want to risk getting that dizzy.