There is a nice ethnographic museum in Stuttgart:
http://www.lindenmuseum.de/html/english/home/home.php
Not many weapons, but a lot to see nevertheless. I'd recommend it.
(There are other good museums in Stuttgart as well - the Württemberg State Museum has a nice collection of Bronze and Iron Age weapons:
http://www.landesmuseum-stuttgart.de/en/index.php)
The Museum in Berlin has a very nice South Sea collection with complete huts and boats!
Peter