I was playing online and this one person [my friends noticed it too] had faster melee speed. At first we thought he was hacking, but when I looked closer it looked like he was using different armor pieces then everyone else.

Here is how my first experience went against him in melee.

I melee'd him from the side, then continued to spam melee button (so that the second I was able to it would melee again)
He then faced me, melee'd, then just before I was able to melee he melee'd me again, my melee then went off sort of from the grave (I get this alot, I don't know about you people, where both people kill each other in melee and its like CLOSE CALL. REVENGE. or something along those lines)

That is less then half the melee time. If it is armor, and not hack, what armor pieces do this?

Further note: I was in a lobby with him and my friends for like an hour or two and this happened multiple times to all of us. But most of the time we just died, not him and us.

I think hes hacking the game. For every piece of armor it says "does not affect gameplay". But maybe you and your friend don't know how to melee properly because it is a lot faster then the Halo 3 melee (which is what I'm used to).

So usually I put on scout and run around beating people down punching them in the face two times.