v.148 - Grand Athenaeum Update Highlights

I don't think it's the 300 damage skin, the colours are different. I want this one too though. Does anyone know if damage skins are seen by everyone, or just the player using them?

True, but the pattern is the same. I imagine they edited it slightly since we won't be getting the 300 event (since it's a White Day event, and we don't have that).
That gives me hope that we will be getting it then, if they went to the effort of changing it.