I don't understand the definition of the perk Deft Movement

[Wolborg]

What does it mean: "10% chance of avoiding all damage from a melee attack?"

 

Does it mean that, on average, every tenth blow that normally would hit me will, thanks to the perk, do 0 damage?

 

Or does it mean that in 10% of combats, none of the blows damage me?

 

(As long as I wear all Light Armor.)

 

[Nergui]

It is the first one. 10% chance per attack made on you of doing no damage.