What is the * besides the % in armor mods?

Title says it all, I'm just curious if it's an extra bonus or something, such as 6%** Xp Bonus, or 9%* Thorns

 

It tells you how good the roll of that identification is
Wynncraft positive item identifications range from 30% to 130% of the base value
rolling lesser than or equal to 100% is zero stars ( )
rolling from 101% to 124% is one star (*)
rolling greater than or equal to 125% is two stars (**)
130% (perfect roll) is three stars (***)

I recommend installing Wynntils, you will see the percentage instead of the stars.