From Dark and Darker Wiki
Most melee weapons operate on a Sweet/Sour Spot system, meaning hitting an enemy with the tip of the weapon will deal the most damage and hitting further down on the blade/haft will deal less damage. The number of sour spots vary between weapons.
Closer you are, worse the long range weapons become. This can affect Polearms badly. On the other hand, daggers always do their 100% damage.