Enemy captives always were good for target practice. You didn't need to feed them, and it was a great show for the citizens. A captive who shot a huge final load always got a round of applause. A good spear thrower could put one right through the navel. Cocks and balls were secondary targets.
I imagine the spear in his gut was the first hit. He may have tried to grab hold of the shaft and pull it part way out of his body as he writhed from the penetration. But when the second spear took out his manhood, he probably just dropped his arms back down and gave up: "fuck it." Last thing he saw before he blacked out was his sperm cascading down in front of his face.
Wow, the placement of that top spear, so hot!