Return to Castle Wolfenstein's Tesla Gun and the one machine gun that blew shit up that I can't remember the name of.
Silent Hill's chainsaw, light saber and steel pipe.
Resident Evil 4's Riot Gun, Punisher and Rocket Launcher. Scoring a direct hit on Salazar with the rocket launcher is a one hit kill. :D
FF7's Ultima Weapon.
FF6's Atma Weapon and Illumina(that big yellow sword you win from the colliseum if you wager the Ragnarok)