All secular evidence doesn't change that crux simplex = 'simple stake' was a form of roman crucifiction/impalement at the time of Jesus's death and could involve a small seat like piece of wood that could be used to take the pressure of his lungs which mean't piecing the victims side would then be needed to cause death.
Actually I once debated this point thoroughly with leolaia but have since done more thorough research and the crucifications/impalements were all different from case to case. but I found what for me is definative proof of stake in the bible, Jesus's own words!
Numbers 21:9
So Moses made a bronze snake and put it up on a pole. Then when anyone was bitten by a snake and looked at the bronze snake, he lived.
John 3:14
Just as Moses lifted up the snake in the desert, so the Son of Man must be lifted up,
This for me is the nail on the head that when the appostles all wrote stake (incidently knowing it implied no shape when they wrote it) that Jesus did die on a stake he fortold it himself quite clearly.