[Keeper of Dol Guldur]

I think we can take Treebeard as honest, after all his words made it into the text, and there aren't any other incidences of him being wholly wrong about things like that.

But anyway, I don't think goblins and orcs have huge, scaly, greenish (did it say green?) toeless hooves of feet. That and Boromir's sword never glanced off the skin of any other orc, and he swung it at many, many of them.

"The Hobbit's bite is deep, you have a good blade, Frodo, son of Drogo." That's what Aragorn said. He didn't merely 'stab at' the Troll's foot, he drove Sting in deep and when it went past possibly two inches of tough, scaly skin (I'd say almost like that of a crocodile). And Boromir was probably more than five times the strength of Frodo - I'd say the weapon mattered TOTALLY.

Granted, Hurin was one of the greatest men ever - but Hurin bore an axe and came out of the East of Beleriand - it's possible that axe was dwarf-made, and Dwarves weapons were possibly of greater craft (though less enchantment) than elven ones in those days (Narsil, anyone?). Also, Trolls being something of a subterranean creature it's likely that Dwarves had many more dealings with them and so the craft of the weapons reflected that knowledge. Couple that with a mighty swing from Hurin into the chest or head of a troll (and they were also lesser in size and strength in those days, yes), and it seems likely if he dropped his shield and only used the axe, that he was assailing them in the berserker style, charging them, using speed and surprise and not letting them have time to defend themselves. Trolls are after all big, dumb and slow, so the berserker attack would work better on them than on Orcs or other Men.

And also - Hurin was taken alive, it's likely he was under explicit orders to be captured alive, and that's why he wasn't killed during his huge exploit, so it's possible he did kill 70 Trolls, with how stupid they are and his attack.

The Troll Pippin killed . . . was a huge troll on the other hand, and a huge feat for one Hobbit, it was well armored and massive. His barrow-blade (and it was that blade), cut right into it's belly. The Numenoreans in Arnor lived close to the Troll-Shaws, and it's likely that many Trolls were in the employ of the Witch-King of Angmar, whose sorceries and servants those blades were warded against (possibly by the elves of Rivendell). Had he screamed "For the Shire!" and stabbed the Troll's foot, it's likely he would have gotten similar (though I doubt as much) results as Frodo.

That raises the question in my mind, as why the Defender of Minas Tirith and the heir to the seat of Stewards, descended in a long line from Mardil, who was distinctly of pure Numenorean descent, wasn't carrying a blade of that history (I speculate the very sword Denethor still wore girt around his waist was the "Blade of Mardil" or whatever - he wasn't ready to part with it yet). But that's another topic.