The Gift of Speech

[Aiwendil]

Gurthang doesn't talk. Turin, or rather Tolkien through Turin, is projecting his other, conflicting personal torments: In his despair he justifies his imminent act (of suicide) by focusing on all the ill-things that he had done with ihis sword i.e. accidently killing Beleg, Brandir etc etc.

That's certainly a valid interpretation, but I wouldn't state it as a simple fact. There is something to be said for taking the text at face value as well.