The space element was indeed very useful for Kate.
In terms of defense, it could completely cover up her surrounding, preventing anything from approaching her with malicious intention. There wouldn't be any attack that could fall to her body.
But at the same time, this space element would block all sound from outside.
It isolated the attack from her.
It also isolated her from the outside world.
When Kyle tried to communicate with Kate normally, the sound waves never reached her because the space element blocked it. Thus, he had to use the second method of communicating, which was through their blood contract.
But this incident also made Kyle thought about Kate's fighting problem in the future.
If she was not with him, how would she communicate with others? The space shield she formed around her body would isolate her from the outside world.
Could she control the shield so that it would allow her ears to listen?