Melee range of players varies according to the range adder of the weapon equipped and the size of the monster being attacked. 
Range = range adder + size
When an Assassin or a Barbarian equips two weapons and attacks a selected target, range is based on the range adder of the primary weapon (the weapon equipped above the gloves in the inventory, or that first equipped). The primary weapon is displayed in the right hand of the Assassin or Barbarian. This is true for Dragon Claw and Double Swing and Frenzy, even though these are a sequence of two attacks (as are Normal Attack and Fists of Fire, Claws of Thunder and Blades of Ice when used with two weapons). While each weapon attacks and applies its damage and modifiers individually, the range applied to both attacks is still that of the primary weapon.