Weird experiments

[BanditAngel]

For a normal bow:
Create arrow
Calculate arrow damage as the sum of all available physical damage sources

For a lightning bow:
Create and calculate arrow as above
Create lightning effect and attach it to arrow
Calculate lightning damage as the sum of all available lightning damage sources

For a fire bow:
As lightning but replace "lightning" with "fire"

For a melee weapon:
Create and calculate a physical blow
Check for lightning & fire damage sources on all gear and create and calculate if found

Hopefully that is a nice simple and accurate explanation of how it works, and therefor why Sparking Mail only stacks with lightning bows but still stacks with any melee weapon.