in testing it I found it to be zero damge. well almost zero damage.
When I attacked a target and had a 14 strength +2 damage. I did 2 damage with every hit.
Same for when I had 12 strength +1 damage . every hit did 1 damage.
When I had 10 strength +0 damage however I still did 1 damage per hit.
So I guess I would call it 0 damage, Minimum 1 damage after modifiers.