Yseult's slow nod follows on the heels of quicker understanding. There's something like empathy in the brief flash of a smile earned by his self-deprecation, and in the way she asks:

"Do you have any portrait of her? Or would you be willing to meet with our artist to have one made? It wouldn't need to be shared widely, if you'd prefer, but it would greatly increase our chances of success. Especially if she isn't easily distinguished and might not travel under her own name." Which seems a safe assumption for anyone Silver cares about.