Sauron's knowledge of the Istari

[Angry Hill Troll]

Merry's sword which was enchanted with a spell from Fornost? was the actual dealing blow. (I seriously doubt this will be covered in the movie ROTK.)

That would indeed be rather hard, considering the chapter where Merry gets the sword was excised from the movie. [img]smilies/rolleyes.gif[/img]

Actually the sword might not be from Fornost, since it was the capital of Arthedain and the Barrow-Downs were in Cardolan (if you want to get technical)