These are the knives that were free for the taking in the dining hall in the 80s & 90s. They were carried by the inmates throughout the prison or hidden in areas where they could be deployed immediately as needed.
The handle from bucket of cleaning fluid is straightened out and the end sharpened into a point.
This is a toilet brush shank. Anything can be a weapon or modified to be a weapon in prison including basic cell effects like this. Metal or plastic it can still kill.