As others pointed out tho, if this were an actual official arena, it would be destroyed in minutes by the Ender Dragon. XD
the regular stone portions would be gone, you'd need a completely new stone type to mimic the texture and color of regular stone and the hardness of obsidian or endstone, while keeping all the vanilla textures intact.
Or you'd need to cheat to modify the hardness values of normal stone,
one of the two.
The look fits, I totally agree with that opinion, but it's impractical.