1. One weapon.
2. One song blasting on the speakers.
3. One famous person to fight beside you.
Weapon may be real or fictional; you may assume endless ammo is applicable; the person may be real or fictional.
The weapon is obviously going to be a Vorpal Blade. Snicker-snack. Off with their heads.
The song blasting on the speakers has to be Oingo Boingo's "Dead Man's Party".
Famous person to fight beside me... may be fictional... Despite my loathing for what she's turned into, I'd have to say Anita Blake would be a good choice. Not that there is a huge shortage of suitable people in fiction.