The video below says that it's all about the making of "Game of Thrones"' elaborate Dornish weaponry, and technically it is -- but that's not the biggest reason why it's so cool.
That would be because said video also includes some coveted behind-the-scenes peeks at Oberyn Martell's daughters, Tyene, Obara, and Nymeria (Rosabell Laurenti Sellers, Keisha Castle-Hughes, and Jessica Henwick, respectively), looking so fierce that you seriously will not be able to stand it.
Each of the women -- known as the Sand Snakes for their Dornish origins and mercenary dispositions -- has a signature weapon, all lovingly crafted by "Game of Thrones" weapons master Tommy Dunne, and it's appropriate that our first look at the ladies shows them holding their particular tools and fully prepared for battle.
Clearly, the Viper's daughters are not okay with the thing that happened to their father at the end of the most recent season, a.k.a the thing we are still not able to discuss without being traumatized afresh by the horror of it, so let's not. Let's just watch the nice video and talk about how good the Snakes look, and also about how cool Areo Hotah's axe is.