[Spoiler] Weird Static Cross?

So, I beat new secret boss, which I'll be detailing more in the post anyone who wandered in here, reasonably spoilery names ahead.

After completing the run said "heck it, rerun button's right there" and noticed in my item bar there's something unusual, a weird static cross. Highly animated actually, unlike any other items as far as I can remember.

https://steamuserimages-a.akamaihd.net/ugc/1710779599194964630/3E25AAE547409E8D4E5C85354F73804F97E45C90/

Looking at youtube videos, it doesn't seem to be in anyone's item bar while fighting Dogma, and then the item bar isn't visible during The Beast Fight, but clearly it's visually connected to Dogma and the cutscene between the two fights.

I did try doing a few searches about 'static cross', 'rerun', etc, before making my own post, but since I didn't pick it up I have no idea what it's called, searching about it isn't ideal.

Anyone know anything about this? It's very visually animated unlike most... all? other items, in the item bar. So far I can't tell what it does, but it feels like it must do something.