Some pikers wield halberds. WB2014_Dylan_and_Thomas_-_Part_1
In the real world, the pike is a very long, two-handed spear that is not thrown. In Erfworld pikes are grouped with other pole weapons with the exeption of short spears, which are grouped with swords as Stabbers. LIAB Text 24 has a nice image that shows a spearman, a swordsman and a piker.
Pikes and spears are traditional anti-'mount' units in most games, and weak to archers and swordsmen. It could be assumed that they carry a bonus to mounted units.