I know It's a relic step but lore wise I bet it's one of the artifacts collected from Citadelle (Since we know a piece of a scroll written by the Owl was collected) by the Thurston cult.
Then when the Planetarium was sent to the dark aether and zombies started to appear one of the cult members probably used the lighting rod as a weapon lmao.
I think we should look deeper into some relic steps because they seem to be Important with the lore as well.