Are you sure these are their first names? Well, I suppose you are, they are distant relatives of yours, but normally there's not a big culture of "word names" here in Germany, and most names like that are not even allowed, I'm especially surprised at Rüstung, while I think that Guteherz COULD be a very old first name, like
Gottlieb and
Gotthilf.
I like
Melchior, but it's really a very grand name, and maybe more apt as a mn. And I like
Joost very much, especially in the north of Germany.