That's not merch, that's the Veil of Veronica. Very significant catholic story/artifact. The story is that when she wiped the blood and sweat off of Jesus his face appeared on the cloth. You'll find depictions of this in most old catholic churches and many paintings
I guess it was like doing Instagram pranks without the internet. "Yoooo, an angel just totally appeared to me" just to get attention back in that days when everyone was bored as fuck. If someone believes your bullshit, and writes it down and hides it for a thousand years, suddenly it's a religious fact
I read somewhere about some secret tooth cherished by some sect that was destroyed by grinding it to dust, mixing with shit and throwing in to the ocean. But guess what? Some fishermen said that he totally found the tooth restored floating on a leaf next to the place where they threw it out. You can't fight believes with real world methods.
"The Veil was owned by the Leonelli family until 1608. Pancrazio Petrucci, a soldier married to Marzia Leonelli, stole the Veil from his father-in-law's house. A few years later, Marzia sold it for 400 scudi to Doctor Donato Antonio De Fabritiis to pay a ransom demand for her husband, who was then a prisoner in Chieti."