I just wrote a story in which someone wields a boathook as a weapon (hence the belated doubtful googling) and so this disconcerted me. I had a clear idea of the sort of boathook I meant, which is the sort that my Dad owned, which was an object you could quite easily kill someone with, possibly by accident.
I had to google some more to discover that I wasn't misremembering the configuration of old boathooks. I remember it as basically a spear with a barb.
What is the spike for? I've always wondered this (particularly when my sister was holding the other end and pointing the sharp bit at me. Oh, how we laughed). Why did it used to be so sharp? (Pirates? :-D )