Hmm. Interesting proposition. I shall abide by the rules of your little game, good sir!
For defence, I would hide behind my spiffy desk chair. It swivels, it's on wheels, and it's more than big enough to hide behind, because I'd be kneeling on it and pushing it along with my foot.
For a weapon, I would use my guitar. Most likely my electric guitar because it has more reach and looks like it would last longer and be easier to swing.