It should be possible to actually get damage from the second sword, but have change the stats of the second sword depending on your melee and then add the damage to your overall damage.
If melee= 0->50
First Weapon + (Second Weapon/5) = Overall
If melee= 50->100
First Weapon + (Second Weapon/4) = Overall
If melee= 100->150
First Weapon + (Second Weapon/3) = Overall
If melee= 150+
First Weapon + (Second Weapon/2) = Overall
So if both weapons hit for 50,
If melee= 0->50
50 + (50/5) = 60
If melee= 50->100
50 + (50/4) = 63
If melee= 100->150
50 + (50/3) = 67
If melee= 150+
50 + (50/2) = 75