I apologize in advance, but is that a difference that makes a difference? Under what circumstance would an "off-hand weapon" be treated differently from a "weapon with the off-hand property?" And how would I tell the difference?
I can imagine (but haven't found yet) a magical weapon that is restricted to "off-hand" weapons only.
I do find it very lame that the intepretation in this thread suggests that you cannot use Power Attack with a versatile weapon that is being used in two hands. If the various two-weapon ranger powers that reference an "off-hand" weapon do not refer to weapons with the "off-hand" property but rather weapons that are being currently wielded in a character's off-hand, why does not that same reasoning apply to a "versatile" weapon being wielded two-handed with Power Attack?
How am I, as a player, supposed to know when a rule is refering to the manner in which the weapon is being wielded, as opposed to a property of the weapon itself?
Smeelbo
For your first question:
It matters because new classes, powers, and feats are being added to the game that make specific references to the property of the weapon, rather than how it is wielded. (Tempest fighters, for example.)
For your last question:
Ask your DM. There are basically two schools of thought:
1) Only the property of the weapon matters. If the weapon is one-handed, it is a one-handed weapon at all times, even if it is versatile and able to be used with two hands.
If the weapon has the off-hand property, it is always has that property, no matter which hand is actually being used to wield it, and if it does not have the off-hand property then it is never treated as having the off-hand property even if you can wield it in your off-hand.
2) How you wield the weapon matters more than the property, and in effect can grant (or remove) that property to the weapon. So wielding a versatile weapon in two-hands makes it count as a two-handed weapon rather than a one handed weapon. Wielding a weapon in your off-hand effectively grants the weapon the off-hand property even if the ability that lets you do this doesn't specifically state it.
So far, Customer Service responses seem to be using Option 1. There is a response from one of the developers that seems to go with option 2, but that is specifically a non-official response, and may not match the current design philosophy. On the other hand, option 2 makes more sense than option 1 to a lot of people.
So ask your DM.
