More fire is great- at least, in theory. Reira's shield certainly holds, but holding it the way she is means that Reira herself isn't especially well protected; while both fireballs are successfully blocked, the girl twitches just slightly as the heat washes over the edges and against her arms.

Any normal child would probably have cried out about it- Reira, at least, seems to be made of stronger stuff when it comes to pain tolerance, though it doesn't keep the shield from flickering for a few moments again. That stings.