Bestiary entry from the Clan Primer:
This creature always drops a trophy when it is defeated. This trophy is used in the Hunt Club side quest which involves trading in the trophies for items, armor and accessories.
|Common - (55%)||(Nothing)|
|Uncommon - (10%)||(Nothing)|
|Rare - (3%)||Destrier Mane|
* Nazarnir has a 40% chance of appearing in the south-east corner of the Starfall Field and replacing the Sleipnir that normally resides there. Just leave the area and re-enter if it does not appear.
Note that you need to have initiated the Hunt Club side quest before Nazarnir will appear.