Arya really needs to get back among the action. Everyone expected Season 5 would encapsulate most of her training with the Faceless Men and while she did begin the process, she ended the season in a worse state than she started it. The poor girl can't even see. With the entire series beginning its gradual descent towards the grand finale, Arya needs to flee back to Westeros or be dispatched to the mainland as an assassin so that she can fulfil a purpose in the main story. She's a great character, but as long as she remains in Braavos, she's not an important one.