I discovered this by wanting to see if manifested weapons from idols got the benefit of passives in Forge Strike. Swinging at the dummy using Vengeance with 30% chance worth of idols equipped I never spawned a weapon. I went to a combat zone and killed several packs of enemies with Vengeance alone and never spawned a weapon.
My thought was it probably only works for Forge Strike. So I went to the dummy. With the skill specialized for 20% additional chance and 30% worth of idols I should be spawning weapons at 70% rate with Forge Strike. My testing returned about a 20% spawn rate.
I know the Forging prefix for Ornate Idols does not work. I also suspect the Mass Production node of Forge Strike also does not work.