They appear to be skill books that increase your stats but I can't tell what they do.

For example, I have one book about trading with a 100 designation. I tried using this before I went to a shop and I saw no difference in prices. Then I tried using it a bunch of times to see if it increased any stat. Nothing. What am I missing here?

The first time you read a book, it will increase your skill(s) by a decent amount, usually 5% or more. Apparently this increase is bigger if you "turn off" all other skills before reading the book (i.e. only have the relevant skill turned on). The "100" is how many times you can read the book before it is destroyed. I tried reading books multiple times, but didn't see any more skill gains after the first time, but I've heard others say that if you read the books over and over, you can increase skills slowly, kind of like how the practice lute will increase barding skill if you use it many times. The first time each character reads it they always get a big skill bump, however. You should see the "Owyn's Haggling skill has increased" message after Owyn (for example) reads the book the first time. Remember that reading a book takes many in-game hours, so you may have to sleep afterwards.

The book on trading should increase your haggling skill. This only affects prices if you actively try to haggle for an item in a shop, and it will never affect selling prices, only buying prices. I'm not entirely sure how the math on the haggling skill works, but you should have a higher chance of successfully haggling for an item, and probably also a higher chance to get a bigger discount.

Next time you find a book, look at your character's skills before reading it, then check them again after to see what increased.

As Walt said, the default prices don't change but a higher Haggling skill gives you a better chance to get a better discount when you choose the haggle option.

Books act as 'training' on subsequent reads by a character. It generally takes a lot of reads to get more skill ups out of it and you'd better make sure the party has a good stock of food if you're reading books repeatedly - especially "Thiful's Bird Migrations", which takes the better part of a day for a single read. (It's the best one to power read because it improves every skill.)

IIRC books may not give the initial large bump to a couple of characters that join the party in later chapters, but they should do so for all of the characters featured in the first three chapters (Locklear, James, Owyn, Gorath), and even the two who don't get the big initial boost will still benefit from power reading.

I should note that I never used books for grinding, just for the initial boost, and had no problems with the game being too hard. So don't feel like you HAVE to grind. Just do it if you want to.

Want to ???

I am an old skool power gamer. I must grind to be the God that I deserve to be. If you invite me to your world, you invite me to rule it . . .

No problem! Just remember that you might want to keep some of your books around so that other characters who will join your party in the future can read them too. It's not always easy to find replacement books.

That is a great point. One great book too late however, but I am only in chp 4.