«...clean grimy hands...»

The word is supposed to be hands.

You will wash hands that are grimy and wash faces that are weary.

Thank you, GG. I would have never looked at it from this angle...

Unless you are talking about specific hands, you do not need an article of any sort. Generic plurals just don't need articles. I would guess that the author was looking for poetic writing, or else he would have probably added the pronoun "your" just as he did for "weary faces". But it isn't necessary.
Hope that helps!

~Miss Mandy

MissMandyHope that helps!

Sure it does!

I hope one wouldn't say similar things when addressing one person: "Hey, Paul, you should wash a weary face."... Somehow it works only with hands ('cause most of us have two ones) and only with more than one person, right?

Anton

Haha, you gave me a funny picture in my head. If you told Paul to wash a weary face, he would probably be looking around for someone else's weary face to wash because you can't tell him to wash his own face that way; a tells the listener that we are being generic. If you wanted him to wash his own weary face, you'd need a possessive determiner (your). So, yes, you seem correct.
When thi

MissMandy...a tells the listener that we are being generic. If you wanted him to wash his own weary face, you'd need a possessive determiner (your)

Hmmm. I thought that a + singular countable noun was the same as zero article + plural countable noun.

Why wouldn't the hobbits look around for other(s)' grimy hands and not their ones? In the origin

Ant_222Hmmm. I thought that a + singular countable noun was the same as zero article + plural countable noun.

You're absolutely right.
The original sentence may have led the hobbits to go looking for others' dirty hands to wash because the author chose to omit the word "your" before "grimy hands". As I said earlier, its seems like it was poetic license

Thank you, MissMandy, for your help and for the tree you sent me!