Winterhoof Emblem is a special quest item recieved from the Skorn Must Fall! quest. It is used to summon a Winterhoof Brave to aid you and your group in three missions he gives out. You return the emblem during The Conqueror of Skorn! quest. Upon returning the emblem to Chieftain Ashtotem you are given the second quest in the chain.
Keeping the emblem for a little bit while longer might be a good idea as he will help you fight any Vykrul you encounter, making it easier for your character to level up.