A Ferrule

1. A band or cap (usually metal) placed around a shaft to reinforce it or to prevent splitting. [from early 17th c.]. https://en.wikipedia.org/wiki/Ferrule
   1. (specifically, climbing) The metal spike at the end of the shaft of an ice axe.
2. A band holding parts of an object together.
   1. A bushing for securing a pipe joint.
   2. A metal sleeve placed inside a gutter at the top.
   3. (billiards) The plastic band attaching the tip to the cue.
   4. (painting) The pinched metal band which holds the bristles of a paintbrush to the shaft