I did the quest Take up Arms where you get the Vilkas Sword. Now, I didn't use magic on him to defeat him. However, once I got the sword to Eorlund Gray-Mane, he asked me to go and give a shield to Aela, which I did. As soon as I left, he started sharpening the blade. Since then, I can't seem to find a way to get it back.
Do you ever get it back? Is this a bug?