Should be straight forward and I own a dictionary. But.
Viper's sting per ESO wiki comes in bow.
People have reported here (not sure if applies in newest patches) that viper's sting can proc off a bow.
So - is melee defined by weapon type (e.g. can non-ranged class skill using equipped DW wpn proc viper's)? Or is melee defined by proximity to enemy as some have reported? Is it a basic light or heavy attack or any weapon type, or does it exclude range?
I've searched, answers so far are outdated and conflicting.
All I can verify so far is viper's sting does not proc off of destro staff basic attack (it's what I had to test at the time - I know it doesn't make sense).