Davros was destroyed at the end of Resurrection of the Daleks: Part Two (1984) when he not only succumbed to the Movellan virus, but the space station he was on was destroyed only moments later. There is no way he could have escaped and survived.
When Natasha fires her laser pistol at the Stengos mutant, she doesn't hold it steady (while the post-production laser effect remains steady as a rock, and clearly not emitting from the muzzle of the pistol).