@vishi Not really. Frog girl said Ragna has the most potential TO BE A KNIGHT but all the others have their own talent and powers that are not Knight related.
Rem is from another country/place where they have a diferente set that may rival the knights
Audin is not only very big but also has the divine power locked inside him, which not even the knights have
Sachsen potential is literally opposed to knights since he's talents are assassin related.
Ragna is really the only one that even had any kind of path that could go the Knight way since he's talent is restricted to 'genius with sword'.