Is anyone able to explain +xxx% elemental damage with attacks?

Hi folks,

got this bow:

1.) Physical Damage: 38-72 (60.5 DPS)
2.) Elemental Damage: 78-110 (cold) + 8-249 (lightning) (244.8 DPS)
3.) Total DPS: 305 (according to path of building and POE Overlay)

Attacks per second: 1.1

{enchant}{rune}Adds 2 to 60 Lightning Damage
Bow Attacks fire an additional Arrow

Adds 78 to 110 Cold Damage
Adds 6 to 189 Lightning Damage
4.) 100% increased Elemental Damage with Attacks
+4 to Level of all Attack Skills
Gain 74 Life per Enemy Killed
25% chance to gain Onslaught on Killing Hits with this Weapon


Now taking the numebrs:
from 1.) Physical (38+72)/2*1.1=60.5
from 2.) Elemental ((78+110)/2+(8+249)/2)*1.1=244.8
from 4.) 244.8

Adds up to 550.1 DPS

Where is the error in my calculation? Am I misunderstanding 4.)?

Thx!

The 100% increased Elemental Damage with Attacks mod is not local to the weapon.

That means it doesn't multiply the inherent elemental damage of the bow, rather it is additive to all the other "increased damage" notes u have in ur build, for example from ur skill tree.

Ur bow still only has 305 base dps.