Lying in that ditch, having just been shot at, Weary shows Billy the knife he carries.
The knife's handle has four rings for Weary's fingers to slip through; these brass knuckles have spikes attached to them.
Weary asks Billy how he would like to be hit be these spiked brass knuckles.
Billy says he would prefer not to.
Weary claims that the three-sided shape of the knife blade makes a wound that won't close.
Weary says Billy doesn't know anything; what do they teach in college, anyway?
Billy says he doesn't know; he was only there for six months, and it was just night school.
Weary thinks Billy doesn't understand anything about gore. But Billy does, because on his wall at home hangs a bloodied crucifix with a detailed statue of Christ on it.