It is a quest item for the miscellaneous quest "Amren's Sword." It is owned by Amren and must be obtained from a radiant dungeon. It can be upgraded with an Iron Ingot but no perk is needed (or available).
The location of Amren's Family Sword is radiant, and therefore completely random. Possible locations are:
- Halted Stream Camp
- Redoran's Retreat
- Silent Moons Camp
- Swindler's Den
- Valtheim Towers – listed as Valtheim Keep
- White River Watch