The katara is an Indian push dagger--a knife used in a punching action. This one includes two German flintlock pistols built into the engraved silver handle.
Link -via You're Not Bulletproof | Photo: Gregg Martin Auctions
P.S. Here's another one that's even more finely crafted.
http://www.gesetze-im-internet.de/waffg_2002/anlage_2_82.html
Alclose look at this annex shows how many things that may be considered as weapons are actually forbidden in germany...