I have to say that making an account on the wiki to fix this (after learning to edit a wiki page, since i never done that) and i think making a post about this is a better way to note it, but feel free to erase this thread after someone has taken notice about.
The wiki article of nettle items says acurately:
Nettle shirt stats are determined by q10stat*sqrt(quality/10) - rounded down for bonuses, rounded up for penalties.
Nettle pants reduce agility by 2 instead of 1 if Q11, still providing Q10 bonuses, thus it is advised to craft the Nettle set before raising your survival over 10. (this last only in nettle pants)
I have noted that q7 gives -1 agi +1 surv as according to this, but i have noted also that q13 and q17 (that "rounded up for penalties" dont seems to work as they give the same) has -2 agi +2 survival AND +1 unarmed combat <--- the wiki dont say a thing about this.
And i think that higher quality clothes will give a nice unarmed combat bonus
I also noted that "fits under armor" also permit equip another one as armor itself, i have right now 4 equiped (2 pants and 2 shirts) for a +8 survival -8 agi and +4 unarmed combat