Give the Spear a Sauroter
PipperChip has the right idea about using it as a walking stick, but kind of dismisses the metal spike on some spears as a problem, when it is actually the solution. The metal spike is called a sauroter. It was invented around 400BCE at the height of the Hoplite revolution after Greek armies transitioned to mainly infantry forces. These armies often had to walk for very long distances with their spears in hand; so, the sauroter was designed to facilitate this.
While the Sauroter is often described as an "extra spear tip" this does not appear to be its primary function at all. Greeks already carried backup weapons (a xiphos or kopis) for if thier spears broke so an extra spear tip would be a silly amount of redundancy, and harder to bring to bare. Furthermore, the spike on the butt of the spear was very different than the spear head. While the spearhead was typically a light weight, thin blade of steel, the spike at the butt of the spear was much thicker, heavier, and made of bronze or brass. It was also blunted as you can plainly see in better preserved examples of them suggesting it was not meant to be used as a stabbing weapon at all.
This choice of metal and design suggests that it was instead made to be able to plant into the ground over and over again without rusting, getting stuck, or braking actually facilitating its ability to turn your spear into a better walking stick than... well a walking stick.
They also functioned as a counterweight to bring spears center of gravity farther back extending the effective range of the spear, but that has nothing to do with them being spike shaped.