I've made done a bit of tinkering these pat few days, and picked up on the fact that Summoners can wear mithral breastplates without penalty, ignoring proficiency penalties by either spending a trait or adding comfort property to the armor.
But what if the Summoner were to wield a mithral light shield, which has an armor check penalty of 0, and a arcane spell failure chance of 0%.
Would the Summoner then incur 15% spell failure for wearing the mithral breastplate?
