I have a lvl 8 Paladin lvl 6 Champion of Torm.
I have a wisdom of 14.
According to what it says about paladin spells, I should be able to cast lvl 4 spells, but I can only cast lvl 2 spells.
(the text about paladin says wisdom cost is 10 + spell level)
Any clue of what is wrong?
Paladin spells
There is nothing wrong, it is more misconception from your part - which I will try to explain 
There is a table in the manual on the Paladins spell progression in the manual where you can see that a paladin starts getting spells from level 4 and onwards. (page 163 in my version)
Now this table says that at level 8 a paladin will be able to cast a base of 1 spell of spell-level 1 and 0 of spell-level 2.
Now you then say your character has a wisdom of 14. That gives according to another table in the manual (page 69 in my version) access to 1 bonus spell of spell-level 1 and spell-level 2.
That means at level 8 your paladin can cast 2 level 1 spells and 1 level 2 spell.
The highest spell level a paladin will ever get to cast is spell-level 4, which the paladin will start getting access to when he reaches level 14 (but only if he has a wisdom of minimum 18 - then otherwise he will reach spells of spell-level 4 at character level 15).
...basically, take a look at the spell progression table for paladins/rangers in the manual (the one on page 163) and modify it with the spell bonus as read from the table showing bonus spells based on ability scores (the one on page 69).
So...
What the "wisdom cost is 10+spell level" means is that you must have that amount in wisdom to be able to cast spells of that spell-level.
It dosen't say that you get access to spells of that spell-level when you have that amount in wisdom.
Hope some of this helps, otherwise - I can try to see if I can explain it better
There is a table in the manual on the Paladins spell progression in the manual where you can see that a paladin starts getting spells from level 4 and onwards. (page 163 in my version)
Now this table says that at level 8 a paladin will be able to cast a base of 1 spell of spell-level 1 and 0 of spell-level 2.
Now you then say your character has a wisdom of 14. That gives according to another table in the manual (page 69 in my version) access to 1 bonus spell of spell-level 1 and spell-level 2.
That means at level 8 your paladin can cast 2 level 1 spells and 1 level 2 spell.
The highest spell level a paladin will ever get to cast is spell-level 4, which the paladin will start getting access to when he reaches level 14 (but only if he has a wisdom of minimum 18 - then otherwise he will reach spells of spell-level 4 at character level 15).
...basically, take a look at the spell progression table for paladins/rangers in the manual (the one on page 163) and modify it with the spell bonus as read from the table showing bonus spells based on ability scores (the one on page 69).
So...
What the "wisdom cost is 10+spell level" means is that you must have that amount in wisdom to be able to cast spells of that spell-level.
It dosen't say that you get access to spells of that spell-level when you have that amount in wisdom.
Hope some of this helps, otherwise - I can try to see if I can explain it better
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