A 19th century American boarding pike

[Jim McDougall]

As someone not especially well initiated in the nautical thing, what is a 'cathead'? or should I say what does it represent (other than the obvious figure).
On the markings, it seems to me that in many areas of equipage, weapons are sans markings. As far as the hafts, these seem to have been remounted with newer ones over years, or obviously if damaged.