Could Loki‘s df be the Hraesvelgr fruit? It could explain the freezing ability, flight, and bipedal silhouette that we saw. It’s like a giant eagle.
Found this in God of War lore:
“It's possible that Hræsvelgr is the one who‘s responsible for causing Helheim to be in a state of permanent deep-freeze, as her mighty wings flapping could be what causes the severe cold winds blowing unceasingly like it does in Norse Mythology.”