No Living Man

[Firefoot]

2. It has to be a midget with hairs on his feet.

I don't think that this is true. Look at the statement again:

No other blade, not though mightier hands had wielded it, would have dealt that foe a wound so bitter, cleaving the undead flesh, breaking the spell that knit his unseen sinews to his will.

The phrase " not though mightier hands had wielded it" is clarifying "no other blade" - not "the blade of Westernesse." It's not saying that only a hobbit wielding the blade of Westernesse could have injured the WK so badly; it's saying that should any other blade been used, even if it had been weilded by the most powerful person in Middle-earth, it could not have had the same effect on the WK. The sentence says nothing about what would have happened if that same most powerful person had been wielding the blade of Westernesse.

e.g. If Merry had used a different sword, the effects would have been less deadly. If Aragorn had used a different sword, as before, the effects would have been less deadly. But if Aragorn had used the Blade of Westernesse...? The statement doesn't say. The emphasis is on the blade being wielded, not the hands that wielded it.