Super-Strenght Power

[Kappa]

This is a power card on Munchkin: Marvel edition

I had a disagreement with a friend recently about what this card really means.
The card says: Each empty hand you have is worth an extra +1.

What I and the others understood from that is that I am getting +1 for each hand Item slot I have free. F.e. If I have an one-hand Item equipped I get +1, a two-hand I get nothing and if I dont have any hand items equipped I get +2.

My friend thinks that this is referring to the number of cards you hold in your hand. F.e. if I hold 3 out of 5 cards that I am allowed in my hand I get +2, if I hold 5 I get nothing and if I don't hold any hands I get +5.

Thank you in advance for your responses.