RangerWickett said:
1. Take a hand off the weapon (free action).
2. Use that hand to cast the spell (standard action).
3. Put your hand back on the weapon and be considered to be wielding
the weapon (free action).
4. Use a move action for whatever you want (move action).
This is absolutely correct, especially given there is no state of being "considered to be weilding". The PC is either performing an action, or being affected by a condition, that prevents him from threatening or he is not; otherwise, as long as the PC is armed and conscious, he threatens.
Ruling otherwise, IMO, severely screws the PC. E.g., in specific reference to greatswords, said caster has already either spent the feat or taken a level in a class that provides proficiency in that weapon, i.e., blowing a feat that could have been used to enhance their core purpose (spellcasting), or sacrificing a level of spellcasting advancement (a
big hit). Invalidating that sacrifice by saying that they cannot use their weapon at all in any round in which they have cast a standard-action (or shorter) spell is a double-whammy, and not in the spirit or letter of the rules at all. (In the case of a cleric using a 2H weapon with which they already have proficiency, balance for this is already built into the class's simple weapon proficiency. The best 2H simple weapons only do 1d8. Big whoop.)
If you're going to do this, then you need to apply the same penalty to any 2H weapon-weilding PC who performs any non-attack standard or move-equivalent action in a round. Which makes no sense whatsoever.
RangerWickett said:
Hell, I'd even let you, if you were wielding a bastard sword without an exotic weapon proficiency, take your hand off the weapon, cast a spell,
make an attack of opportunity in the middle of casting a spell with a -4 nonproficiency penalty, and then put your hand back on the weapon.
Technically, a spellcasting PC does not threaten. The situation you describe could only happen while the PC was casting a spell with a 1 round or longer casting time, and at no time
during the casting does the spellcaster threaten.
Though they certainly threaten
before or after casting, of course.