This episode was very underwhelming and dumb, one of the worst of the series. The Blackfish was wasted and the whole Arya stuff was full of some of the dumbest clichés in Hollywood,
almost as bad as Arrow's Oliver Queen surviving after falling off a cliff.
It was bad writing and completely unnecessary, even on this show, when people get stabbed like that, they usually die, but because Arya can't die yet, they wrote this nonsense instead of just letting her escape with some cuts and bruises. Then she gets cured by the greatest nurse in the world/actress Lady Crane, then recovers just in time to fight the waif, and despite being injured and bleeding (again!!), she beats her offscreen, how wonderful!! Ladies and gentlemen, the new Wonder Girl, Arya Stark!!!
They turned "expert killer" waif into a joke, the idiot apparently can't stab properly and kill a wounded girl with less experience, whatever DB and DBW... They have also ruined Jaime this season by making him Cersei's b i t c h, he's much better written in the books. Also Jon's resurrection was lame, there are no consequences, no price to pay, it's just too easy and lazy. It's really a shame, but the best is yet to come, hopefully, it will be worth it.