Many pathfinder classes have features that allow the character to make selections among many alternatives: for example, witch hexes, rogue talents, barbarian rage powers, ranger favored enemies or terrains, and so forth.
There are a lot of items that, when worn by a member of a particular class, grant the wearer use of a particular selection for these class features (and sometimes enhance the given selection if the character already has it). For example, we have:
If the wearer is a rogue, she gains the resiliency rogue talent.
A ranger wearing the boots can treat the corresponding environment of the boots as one of his favored terrains, granting him a +2 bonus.
I am wondering how the Use Magic Device skill interacts with these kinds of items. I see a number of interpretive difficulties here.
You can use UMD to emulate a class feature, but these kinds of items are written in such a way that they do not call out specific class features, but rather the state of being a member of a class: "If the wearer is a rogue", "If the wearer is a witch", etc., as opposed to "If the wearer has the hex class feature," "if the wearer has the favored terrain class feature," etc. Does the "emulate a class feature" ability allow the wearer to "appear" as if they belong to a certain class?
According to the UMD rules, "This skill does not let you actually use the class feature of another class. It just lets you activate items as if you had that class feature." It's not clear whether an item's granting, say, a witch hex, a rogue talent, or a favored terrain is enhancing an existing hex/talent/terrain class feature, or rather if granting a selection for these features is actually granting the wearer and instance of the class feature. So do these items grant selections for these class features to successful UMD-users that lack it?