Whenever I rest one of the messages that I receive after resting says "Dervish only gain an AC bonus when wearing light armour or no armour"
The thing is though that I am wearing light armour - Mithril chain mail. I thought that maybe the mithril effect wasn't working so that the armour was being read as medium still, but I still get the same message when wearing a mithril chain shirt which has a base armour type of light.
I have tried various combinations of resting/armour on/armour off and it looks to me like the +2 dodge bonus from the dervish isn't applied when I am in a mithril chain shirt.
When I completely remove my armour and then rest the "Dervish only gain an AC bonus when wearing light armour or no armour" message does not appear.
My character is currently a Swashbuckler 7/Dervish 7/Divine Seeker 1/Anointed Knight 4
The other thing is that if I activate my dervish dance, and then rest before the dance effect has ended, I still end up getting the fatigue penalty some time after I have finished resting, at the point where I presume the dance is scheduled to end. So it looks to me like resting doesn't end the dervish dance effect and consequent penalty.