Could a hobbit have done it?

[Imladris]

I wasn't sure which forum to post this in so here goes. I also did a search for this topic and didn't come up with a thing.

In RotK it says this:

[The Witch king is speaking] 'Hinder me? Thou fool. No living man may hinder me!'

... "But no living man am I! You look upon a woman. Eowyn I am, Eomund's daughter. You stand between me and my lord and kin...

But suddenly he too stumbled forward with a cry of bitter pain, and his stroke went wide, driving into the ground. Merry[s sword had stabbed him from hehind, shearing through the black mantle, and passing up beneath the hauberk had pierced the sinew behind his mighty knee.

Now, I am well aware that the Witch king was wounded by Merry's dagger (I heard that somewhere) but this is what Tom Bombadil says of them:

Then he told them that these blades were forged many long years ago by Men of Westernesse: they were foes of the Dark Lord, but they were overcome by the evil king of Carn Dum in the Land of Angmar.

So, if the evil king conquered them (I assume Tom is talking of the witch king), then how could the properties of the dagger be responsible for the nazgul's injury?

So, could Merry have slayed the Witch-king? From what I understand, he is technically not a man, but a hobbit -- a male hobbit albeit but not a man. If he had stabbed the witch-king in the head, like Eowyn, could he have killed him? Could the Witch king be saying that only a Male Man could kill him? Granted, the chances of a hobbit slaying the witch king are highly unlikely, but is it possible?

Forgive me if this questioned is answered in either the forums/books. I did a search and was not able to find it.

Cheers!
Istawen