In the pre-final version of the Conan 2d20 rules you could choose to Dodge or Parry as a Reaction, Dodge used the Acrobatics skill, Parry the Parry skill. (That is the way it was handled in Mutant Chronicles or Infinity, the predecessors of Conan - but in those two games you don’t have a dedicated Parry skill, you simple parry using your Melee skill, you dodge using your Acrobatics skill.)
There had been lengthy discussions on Google+ about some players maxing out their Agility and thus being able to attack using Melee and dodge using Acrobatics very well, making the Parry skill and Coordination attribute unnecessary for a close combat character.
To make the Parry skill more attractive, the option to make a Dodge Reaction versus Melee attacks was removed. Dodge now only is applicable versus Ranged Combat attacks and always generates Doom - as usual for Reactions.
With the “Pantherish Twist” Talent, the Doom cost is reduced by one point, and you are allowed to use the Dodge Reaction to defend against Melee attacks. Without this Talent you cannot Dodge a Melee attack at all.
(This is similar to the “Reflexive Block” Talent (Parry) which allows to use the Parry skill to make a defense against Ranged Combat attacks. Without this Talent you cannot Parry a Ranged Combat attack at all.)
The Parry skill encompasses not only binding/parrying the opponent’s weapons, but also footwork, evasion, weaving, ducking, etc. - so it is applicable even if you are an unarmed defender.
If you are unarmed, your Reach is 1, so every attacker will not have any raised Difficulty due to longer Reach of the defender as Reach 1 is the minimum Reach you can have. Other than that, there is no advantage or disadvantage for an unarmed defender.