Dang, you know some stuff. You're name isn't Robert Langdon, is it?
Nah, my degrees are all in actual fields, not "Symbology." (/snark)
(This thread happens to be squarely in my areas of knowledge; Ancient—Medieval history, and The Big Three of English Lit (Shakespeare, Milton, and Chaucer).) My knowledge (and interest) in History starts in Classical Greece and pretty much stops at the Magna Carta. The Crusades are a special interest, and a lot of that has to do with Arabic/Islamic/Christian relics and iconography, so a lot of my study was focused on that.
While I don’t think it will actually make an appearance, I would love to see a reference to The Holy Prepuce. If anything would have had the blood of Christ on it, I think the leftovers from his circumcision are a safe bet. And that’s exactly the kind of thing Harry would encounter because it’s just that ridiculous that someone would try to weaponize it.
On a more serious note, it’s highly possible in my opinion that other major artifacts will become relevant. Judas’ Noose and the Denarii are a good example. I’m curious if David’s sling or the stone that felled Goliath might make an appearance for instance.
Hmm. There's a lot of fun to be had with imagining what Biblical relics may show up. The sling is a good one. How about:
1. The Horn of Jericho (Used to destroy the walls of Jericho)
2. The Rod of Aaron (Egyptian Plagues; Aaron was Moses's front man)
3. The Ring of Solomon (Jewish mystic and occultist object, supposedly let Solomon command Djinn or demons. Fun fact: the depiction of the seal is what became the Star of David around the fifteenth century)
4. A lock of Samson's Hair (or, like, Delilah's scarf or something)
5. Maybe the crop Jesus fashioned to chase out the moneylenders?
6. How about a branch from the fig tree Jesus destroyed?
7. Betcha money that Hades has the Ark of the Covenant.
8. The sacrificial knife Abraham was going to use to kill his son (Medea's Bodkin?)
There's likely a ton of others, most of which I could find a use for, so I'm sure Jim could.