Game of Thrones season 6 - Arya’s stabbing: Plot twist impending, or just bad writing?

In Game of Thrones season 6 episode 7 - ‘The Broken Man’ - we all got a little distracted by The Hound and little Lady Lyanna Mormont, but there were pretty dramatic events in Braavos, with Arya Stark getting repeatedly stabbed by the Waif.

It was a weird scene and has been playing on my mind in the days following.

Why did Arya, who knew Jaqen and the Waif would be after her, stand in such an open, vulnerable space, staring at the horizon and leaving herself open to attack? Why did she saunter about Braavos so carelessly? Why didn’t she disguise herself? Why didn’t she have Needle? Why was she throwing around bags of coins like its payday in Essos? Why did the Waif stab her in the gut and not slit her throat?

On one side of the debate are the optimists, who believe a secret plan is underway that will be revealed next episode - chiefly that the Arya we saw in the episode was in fact Jaqen H’ghar.

Some of the bad/shaky arguments for it, and why they’re bad/shaky.

- She is seen using her right hand throughout her ep 7 scenes, when her dominant hand, her sword hand, is her left

When your abdomen is bleeding profusely, I think you’d clutch it with any hand.

- Her mannerisms seem off throughout

They do, but this might just be a reflection of her walking/holding herself as Arya now, rather than just ‘A Girl’.

- She tells the man headed toward Westeros “I want a cabin,” when in S04E10 while trying to get to Braavos she said that she “wouldn’t need a cabin”

On the way out she was seeking to be humbled, but on the way home she is trying to become her noble self again.

- Arya previously named Jaqen H’ghar as one of the names on her kill list to his face

True, but she later rescinded it when he did her many favours.

- Jaqen is wearing Arya’s face

But isn’t the whole point that the Faceless Men can only impersonate the dead? This would undermine their whole mythology.

Some of the good/plausible arguments and why they’re good/plausible:

- At the end of episode 6 she slept next to Needle, aware that she might have to defend herself from the Waif

Indeed, so why wouldn’t she be carrying her sword now the situation is even more desperate?

- The old lady the Waif was pretending to be, we’ve seen before

They might have just wanted to include a face from earlier in the show for continuity’s sake, but it’s definitely odd the same old lady was used that Arya had previously studied, and that she didn’t recognise her on the bridge.

I really hope there is something else at work here, as the alternative is that it’s simply shoddy writing.

I don’t buy that Arya would be so preoccupied with daydreaming about home that she would leave herself open to ambush, nor that the Waif would accept ‘a few stabs and then dump in the water’ as an adequate assassination (hasn’t she seen The Bourne Ultimatum?!).

The signs are good for some sort of plot twist though, as the trailer for episode 8, interestingly titled ‘No One’, sees the supposedly severely injured Arya leaping energetically through town.