-ASIAN GUERRILLA MACHETE - After living in the Philippines for two years, machetes and knives became some of my favorite tools and weapons. Hades finds one of these in the death maze during his first fight (he takes it from one of his defeated opponents).
-BALLISTIC KNIFE - I ran across this by accident when searching google for an image of a Soviet era knife. It's basically like a gun that uses different methods to propel a knife blade at a target. They are currently illegal for use by those other than the US Armed Forces (with a couple of exceptions) but can be classified as a gun (and therefore legal) if an explosive charge shoots out the knife.
-VIKING BEARDED AXE - The main weapon that Hades carries on his back will be a modified Viking bearded axe. I've thought about some other types and I'm not sure on this one yet, but having him favoring a Viking era axe feels right.
That's all I have for now. Let me know if you have any other ideas, as I'd like to make his weapon collection vast and unique.