Crime is not that high in Munich. The Olympia Park Area is realitively highrise apartment bulidings and not a nice looking area but not really dangerous. It´s close to the Hasenbergel which is kinda ruff, but there is nothing to see there anyway. Take a trip down to Schwabing around the University, Spend some time near the Gärtnerplatz, which is close to the Viktualienmarkt. Lot´s of nice bars there. You can carry any folder length as far a I know in Munich, I do it all the time. Yet don´t think of trying to bring em into a disco. I worked the doors there and i would take your knife...
If you wanna see a really cool knifeshop go to Helmut Lehner Burgstr 10 near Marienplatz.
happy trails
Matthias