Ability description:

 

"The barbarian swings viciously in a lightning-quick flurry, taking on all comers. Each equipped weapon attacks every nearby enemy, doing extra damage and inflicting Carnage if applicable."

 

 

In my game play, it appears that my character only damages enemies with the current dual wielding weapons equipped (slot 1) and other weapons in my 2, 3, 4 equipment slot does nothing. Is it intentional that barbarian only use 1 slot of weapon when this ability is activated?

Yeah, it means with his current weapon set.

It's intentional.

 

Why do you ask the same question twice although I already explained it to you in the Deadfire forum (with reference to PoE)?