"Flaps" writes:

Too easy to be accused of carrying a concealed weapon.
Wear the katana across your back, they'll get the idea.
What's the big katana called, dai-katana? ;-)
For visual effect, a sheathed bokken would probably suffice.
Mitch.

Or how about a full-length Indonesian machete mounted on your bike?
have a look at techtip 16 for how to mount it:
http://www.wildasia.net/main/article.cfm?articleID=97

Order a Swiss Army Bike. They have an elite bicycle corps, and
the bikes come complete with machine-gun mounts (or some sort
of way of mounting a weapon considerably larger than a pistol.)

It seems that in certain types of terrain, they can move men and
supplies on the ground faster by bicycle than by any other means,
plus you can hide the bicycles in barns and other places when not
actually moving.

--
My real name backwards: nemuaZ lliB