Noticing the eye slits in all these helmets all I could think of was how the English archers at Agincourt dispatched the dismounted and mud trapped French knights. Those slits were just wide enough for a long bodkin to get past.
When he was about 16, Henry V got shot through the face with a bodkin point (his visor was raised) that lodged in the back of his skull. The story of how they got the point out is fascinating and horrifying.