I'm looing for a series of books I read in the early 2000s in Germany (I think it was a translation from English, I remember 3 books with a yellowish color). It was a medieval/fantasy setting, contained lots of fighting and at least one siege.
In one of the books, the main protagonist prepares a bow out of the body of his friends/enemies child and gifts it to the father. He uses bones for the structure, sinews of the string, prepares the glue from the body too. The whole process was written fairly detailed but in a technical/detached matter.