01 - Greater Healing Potion

02 - Broadhead Arrow (3)

03 - Doorway Puzzle
You need to flip a switch and then press the button on the other side in a certain order.
The hidden signs in the library hint towards which order to flip them. As the note at 05 says, you need to run around the pillars to see the signs. When you do, it will cause a castle guard to appear somewhere in the library, and you'll need to be prepared to fight him. The last pillar will even trigger 2 castle guards to appear.

So, you have 3 signs each listing 2 numbers, the first number (written in words) indicates which lever to flip first. And the second number (written in Roman numerals) tells you how to recognise it. It represents the amount of click you hear when pressing the button.
So, if you hear five clicks, that means this lever combination represents the second step.

First (2 clicks):
Pull the middle lever down (others stay up)

Second (5 clicks):
Pull the left and right lever down (middle one stays up)

Third (3 clicks):
Pull the middle lever down and the right lever down (left one stays up)

04 - Sign

Two V

This sign only shows up after running around this column 3 times. This sign hints on how to solve the doorway puzzle at 03

05 - Resurrection Potion, Note

Around the lone pillars. Don't let tired feet stop you

This note is also part of the doorway puzzle, it tells you to run around the pillars to see the signs that appear.

06 - Ancient map

The paper of this map is so ancient it almost crumbles in your hands

We have found no use for it yet, as the description of the map indicates.

07 - Blooddrop Cap (4)

08 - Etherweed (3)

09 - Sign

One II

This sign only shows up after running around this column 3 times. This sign hints on how to solve the doorway puzzle at 03

10 - Pellets (10)

11 - Sign

Three III

This sign only shows up after running around this column 3 times. This sign hints on how to solve the doorway puzzle at 03