'Polearm' can also refer to the weapon type.
The Polearm is a weapon from the base set.
Rulings and ErrataEdit
The Polearm is currently listed as an edged weapon, but it may gain the new weapon type polearm that was release with Towers of Ruin.
Official Glossary entry from 1.4 RulesEdit
A Hero with a Strength of 2 can equip the Polearm for an Attack bonus of +2. A Hero with a Strength of 8 or higher gains +6 instead.