Unknown bug with armour scrap and accidental runeforging

Not sure if this Is a known bug or not, but I had just bought a shield with 0 runic ward on it and no quality. After buying armour scraps from Angie at my hideout I started adding them from my inventory to the shield, and somewhere between 0-15% quality I got 41 runeforge added on, losing around 100 base armour from the shield itself. I know I didn't throw it into the anvil, and I know I didn't have any Verisium in my inventory prior to adding the Armour Scraps.