cipher - Six Series, Six Words

Update: I've just realized the image had a major flaw in it. I've added a new image and made sure it's correct. Nothing else has changed, only the image. Sorry for the inconvenience.

I have six words that all start with "a". Each word is specific to one of these six book series:

A Song of Ice and Fire
Harry Potter
His Dark Materials
Redwall
Sherlock Holmes
The Lord of the Rings

Each word occurs at least once in the canon of its respective series, but almost certainly never occurs in the canon of any of the other series. The words are not necessarily standard English.

This image encodes all six words. Can you figure out what they all are?

Hint:

Each of the secret words relates to one of these six words (given in random order):
changer healer teller river maimer treasure

Verification:

To verify your answer without asking me, put your six guessed words in the same order as their series are in above. Make them all lowercase and separate them with single spaces. e.g.

asoiafword hpword hdmword rword shword lotrword

Take the MD5 hash of this string. If you get 66a8a3195f64cb095da3643c7731c0f5 then you've got the answer exactly correct!

Answer

Solution below.

First, an analysis of the (updated) image:

The brightness values in the image are all multiples of 4. Dividing by 4 gives the following grid:

21 12 21 11 18 22 8 25 12
5 14 17 25 13 5 25 25 19

6 13 8 7 11 7 25 13 25
17 21 13 6 19 21 18 25 19
12 25 25 7 21 11 11 8 6

The most common numbers are 25 followed by 21. Combined with the number range (5-25) it seems likely that these are letters, with 25 being 'a', 24 being 'b, 21 'e' and so on. The grid is then as follows:

e n e o h d r a n
u l i a m u a a g
t m r s o s a m a
i e m t g e h a g
n a a s e o o r t

This contains the letters for many of the solutions suggested elsewhere, though in no obvious order. There are two u's, so animagus/anduin/asmodeus can't all be right. (The originally uploaded image had one fewer values–a 5 ('u')–though the ordering was different.)

Based on this:

The letter distribution is a: 9, e: 5, m: 4, o: 4, r: 3, s: 3, n: 3, g: 3, t: 3, I: 2, h: 2, u: 2, d: 1, l: 1.
From the other suggestions, we can see that aemon/animagus/alethiometer/asmodeus/agra/? fits, leaving "aaorngth". A Tolkien Dictionary indicates the final word: argonath. And indeed this gives the correct MD5 hash.

Solution

A Song of Ice and Fire: aemon (healer)
Harry Potter: animagus (changer)
His Dark Materials: alethiometer (teller)
Redwall: asmodeus (maimer)
Sherlock Holmes: agra (treasure)

The Lord of the Rings: argonath (river)