It's a TRAP

Holding her fist out still before kicking off the wall and landing gently on the ground. She realized that her entire right arm has split right open from the sheer impact of replaying Jon's attacks, and the healing process is so much slower than her usual wounds. Underneath the mechanical compartments and artificial muscles, a thick fluid of red flowed around her body.

Covering it immediately with the other arm, Ally quickly ran off, leaving the treasure behind.

That was what she's truly capable of. The power of Perfect Replay, and the ability to surpass her physical limits by drawing on her combat experience. However, it is clear that if she tried to copy the attacks way above her current capabilities, then she will suffer severe injuries.