In Episode 7 alone;
- Charlie refers to the Angels as "an invincible Exorcist army".
- Alastor says "they're not as indestructable as they appear".
- Charlie tells Vaggie that Carmilla knows how to harm Angels, something Vaggie herself didn't know was possible.
- Carmilla explains that Vaggie fights like someone unafraid of harm, just like all Exorcists.
- Carmilla asks if Vaggie knew that it was possible to harm Angels, Vaggie says she didn't know.
None of this points to the idea that Angels just have... the same immortality that Sinners do. It all points to them being incapable of taking damage normally.
And they aren't just a no-sell above Demons, as Charlie– who is way stronger than anyone in Hell not named Lucy– also believed that the common Exorcists were indestructable despite her being able to fight Adam (
far stronger than the Exorcists), and even catch his punch. She only damaged Adam with the angelic Trident she was using.