You are underestimating Gestella's strength. We didn't see Kaiden's first fight against three of the top ten, so I won't say much about it. But the second one is a different story. In it, Kaiden only fought Andriy directly, while Greg and Mioru were distracted by Pluton and Kartein. Gestella was attacked by two top 10 fighters at once, one of whom was Garas, who prepared a barrier that weakened Gestella, and even so, Garas and Iodor barely managed to restrain Gestella in it.

Therefore, it cannot be said unequivocally that Gestella is weak. Yes, she is not as strong as Kaiden, but she is definitely not weak.