Quality 9 purple weapons have one skin each, same one as Quality 10 Blues.
Availability: Crafting or drops. It would probably be easiest to craft Quality 10 Blue weapons to get the skin you are after.
Quality 9 weapons have three potential skins. Which skin you get while crafting is random. You usually can’t tell by the item icon in the crafting panel which skin it will be.
Availability: Crafting and drops. Mission details to come.