UMD and proficiency

[Chronos]

A character with Use Magic Device can (with a successful check) use a magic item as if they had some class feature that they lack. Magic weapons and armor are examples of magic items. Some classes have proficiency with certain weapons and armors as one of their class features. Could a rogue with UMD emulate, say, a fighter, to use a greataxe +1 as if she had proficiency in it?

[AvatarVecna]

A character with Use Magic Device can (with a successful check) use a magic item as if they had some class feature that they lack. Magic weapons and armor are examples of magic items. Some classes have proficiency with certain weapons and armors as one of their class features. Could a rogue with UMD emulate, say, a fighter, to use a greataxe +1 as if she had proficiency in it?

I think UMD is about tricking the magic of the item into think you're a valid user (so it wpuld allow you to hold/use a fighter restricted weapon), but that wouldn't change the weight or balance of the item and your familiarity with wielding such a weapon.

That's how I understand the rules anyway; I'm not sure if that's RAW or not.

[Chronos]

Yeah, I agree that it seems like that's the way it should work, but the question here is, according to the rules, how it actually does work.

[AvatarVecna]

Yeah, I agree that it seems like that's the way it should work, but the question here is, according to the rules, how it actually does work.

Alright then, let's bust out some quotes:


Emulate a Class Feature
Sometimes you need to use a class feature to activate a magic item. In this case, your effective level in the emulated class equals your Use Magic Device check result minus 20. 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. If the class whose feature you are emulating has an alignment requirement, you must meet it, either honestly or by emulating an appropriate alignment with a separate Use Magic Device check (see above).

The parts I've emphasized are important distinctions; namely, UMD doesn't give you the class features of other classes, it just lets you act as if you possess those class features for the purposes of activating the item. There is no part of a +1 Greataxe that requires activation, all of the magic is a continuous benefit (that you're already getting even without being a Fighter). If there are no activate-able abilities tied to class features, emulating class features via UMD doesn't help you.

It's also worth mentioning that, while attempting a UMD check requires no action, you can't attempt to UMD the same magic item for 24 hours after rolling a nat 1 (if the nat 1 failed), but that's neither here nor there.

EDIT: It's also worth mentioning that weapon proficiency is definitely a class feature, but because proficiency is not required to use the item, emulating that class feature can't help you. That being said, this particular use of UMD might help you use an Iron "Horn of Valhalla" consequence-free, since that item has an activate-able ability that requires proficiency with all martial weapons to not suffer the consequences, but because proficiency isn't a requirement of activation, that would also fall under RAI (in that case, I'd probably allow it myself).