I think Avari is more likely than Celeborn, for sure, but I doubt Avari as well, because Avari have no reason to learn Quenya and wouldn't wear armor with the Finwë stars on it (because they specifically rejected Finwë's leadership when they refused to undertake the Great Journey to Valinor). Might just be the show's way of ensuring we thought "Elf", tho, not specifically Finwë-related. 🤷🏻