Alena is about to attack Natalia with her full power. Even if the difference barrier was not activated she would stop that attack. But because she wanted to check the defense necklace she only focused on attacking Natalia. Natalia on other hand did not make any more; she just stood there without doing anything.
But really, when she feels the power of her sister she almost gets scared. The pressure release from an S-grade is really very powerful. Fortunately, Alena did not release her full pressure and because of this, Natalia Still standing. But still, Natalia feels that she is about to die. At this time she completely forgot about the difference barrier and she also already forgot that it was just a sparring match to check the defense necklace.
