Flanged heads, spiked stars, and the business ends of hafted weapons.
A mace head is a compact mass on a socket: Bronze Age and earlier examples are drilled stone balls; medieval war maces are copper alloy or iron with cast knobs or, later, vertical flanges to bite armour. Polearms — halberds, bills, glaives — leave long iron heads combining blade, spike, and hook in ways that identify the type.
Watch for impostors: agricultural billhooks and hedging tools are the ancestors and cousins of war bills, and many 'halberds' in barns are Victorian ceremonial pieces. Genuine medieval polearm heads show laminated forging, langets (side straps) for the haft, and honest battle-or-sharpening wear.
These are big finds that deserve careful recording: total length, blade and socket dimensions, weight, and section drawings if you can manage them. Provenance is everything for weapons — where and how it surfaced matters as much as the object.
Identifying arrow and spearheads
Identifying swords and daggers