You said you will be working "... in an office environment where, though it's pretty casual, nothing even remotely resembling a weapon will be considered acceptable..."

I'm rather curious as to what kind of office you are referring. Casual dress usually goes hand in glove with casual attitudes.

I myself work with the IT guys in the back room of our casual offices. Anything up to a flamethrower would be acceptable, and they would be willing to discuss the flamethrower. The feeling is, "How cool is it?"

The cooler the gadget, the more acceptable.

As far as "weapons" go, letter openers available at your local Staples would make great stabbing daggers. A long, thin, piece of metal like that would slide right through flesh.

A sharpened pencil would also make for a dagger, as would your average high-end pen. Click the pen point down and you are all set.

Your average PC repair kit contains all kinds of "weapons," should one choose to look at such tools in that way.

Craig