An Answer

Edward knew most things about Anabelle, and vice versa.

Their extremely straightforward relationship allowed the young martial artist to know about Anabelle's mana core grade, ultimately giving her the ability to use Mana and perform Magic.

No, to simply call it an 'ability' would not do it justice. Simply put, Anabelle was talented at Magic. With no tutor, she was able to sense mana freely and even use her Mana core which she established at an early age.

Anabelle was a genius!

However…

"I won't use Magic! It wouldn't be fair!"

… Anabelle had decided not to sully her rivalry with the inept man who became the famous Great Sage, Lewis Griffith. In her own words, she wanted to surpass him using pure wits alone.

Edward, who couldn't understand the refusal to use all that existed in one's arsenal to achieve greatness, had tried to protest. However, after seeing the determination in Anabelle's eyes, and her pure resolve to stick to this ideal, he gave up on the thought.