Old John's words were not an exaggeration; he had indeed identified a problem with Sherry.
Both Ethan and Sherry were aware of this issue as well.
It traced back to their first meeting in the Red Jade Valley, where Ethan discerned an issue in Sherry's Bloodline.
Her lineage was not whole, causing some of the skills she wielded to be fragmented as well.
However, since Sherry did not exhibit any adverse conditions, neither of them paid much heed to it.
Now, with Old John highlighting the inherent danger, Ethan couldn't help but feel anxious.
"Can alchemy complete Sherry's Bloodline?" Ethan asked straightforwardly, assuming that Old John pointed out the issue to persuade him to study alchemy.