Skybreaker The Returned

Would Groot be part of The Church of The Stick?  Could The Stick cross universes?

So by that logic, could the half shard shields that they talk about in Oathbringer be made of Aluminum? That might explain why they are able to withstand a few hits from a Shardblade. Or are the half shards just trapped spren in fabrials that can change their shape like radiant spren can, but since they are in a fabrial and not actually bound to the physical realm or a person because there is no oath holding them in form?

So Nightblood can cut through all three realms, does that mean that by using nightblood, someone could kill a spren, therefore stripping a radiant of their power?