When the point of your weapon is heavier, you have to not only lift the weapon, but cancel out the torque from the unbalanced weight. The further away the point of the weapon is, the more torque, and the more effort. So the additional weight of a halberd has an outsized effect on a polearm compared to the same weight on a shorter weapon like a sword. A halberd will tire out your arms faster and you’ll make more mistakes.

This is why spears are the superior weapon.