I apologize if this has been asked/answered elsewhere. I have looked, but can't seem to find a definitive answer.
Assuming a ranger has taken the necessary Heavy Armor Proficiency feat, can that oh so proficient ranger wear heavy armors made of Mithral and still use their combat style feats?
The description of how mitrhal effects armor seems to suggest this should work. Then again - the description of the Ranger's CSF entry is fairly blunt. To quote the rules in question:
"Most mithral armors are one category lighter than normal for purposes of movement and other limitations."
"The benefits of the ranger’s chosen style feats apply only when he wears light, medium, or no armor. He loses all benefits of his combat style feats when wearing heavy armor."
Does the ranger's CSF restriction fall under the rather-open-to-interpretation 'other limitations?'
Mithral armor: What exactly does it mean when it says mithral armor is counted as one category lighter for “other limitations?”
This means that mithral armor allows its wearer to use it when her own class features or special abilities demand her to wear lighter armor; in other words, the character wearing the armor is less limited. For example, a bard can cast spells in mithral breastplate without arcane spell failure, a barbarian can use her fast movement in mithral fullplate, a ranger can use his combat style in mithral fullplate, brawlers, swashbucklers, and gunslingers can keep their nimble bonus in mithral breastplate, rogues keep evasion in mithral breastplate, a brawler can flurry in mithral breastplate, characters without Endurance can sleep in mithral breastplate without becoming fatigued, and so on. It does not change the armor’s actual category, which means that you can still store a creature one size category larger in a hosteling mithral fullplate, and you can’t enhance a mithral breastplate with special abilities that require it to be light armor, like brawling (though you could enhance it with special abilities that require it to be medium armor), and so on.