In Lord of the Rings The Two Towers king Theoden says the following line:
Saruman’s arm would have grown long indeed if he hopes to reach us here.
As a non native speaker I would have said it like this:
Saruman’s arm would have to grow long indeed if he hopes to reach us here.
I wonder if the first sentence is idiomatic and if it makes sense. It feels a bit off to me. Can anyone explain?
Just as a reference, the official translation on my language would be something like this translated back to English:
Saruman is wrong if he thinks he can reach us here.
As suggested in the comments, Tolkien’s sentence is (we can assume) exactly what he intended to write.
The structure is a conditional: If it is true that Saruman hopes to reach ‘us’ then Saruman’s arm would need to have already grown very long. Of course the reference to his "arm" is figurative.
That makes sense. If your arm is short then you don’t hope to reach very far.
The style is "heightened". Tolkien’s characters, especially his kings, elves, and wizards speak in a "noble" style, in contrast to the Hobbits who are plain speaking.