I am trying to remember the name of a book I read back in the 1980's about a guy who carried a singing sword named Lark. Does anyone remember this story or sword?

I am trying to remember the name of a book I read back in the 1980's about a guy who carried a singing sword named Lark.

Some additional details:

• It was quest style and I feel like it was written by a sci-fi author of renown - maybe Poul Anderson or someone in his era.
• I seem to recall either from the cover or description that the sword was a straight sword that came to a two side point like the tip of a narrow triangle and the guard was circular/semi globe. It was light gray in color.

Does anyone remember this story or sword?