Episode VI: Luke's Shot Hand
In Return of the Jedi, when Luke is cutting down Jabba's minions, one of Jabba's soldiers shoots Luke's mechanical hand while Luke was holding his saber up in the air.
The scene just shows him in a defensive stance before the shooter came up, but then he was suddenly holding his lightsaber up like it was Mjölnir, and got shot in the hand because of it.
So, my question is, what exactly was Luke doing with his lightsaber then? There were no enemies nearby to defend against, and most certainly there wasn't one above him, so why was the saber held up the way it was?