Ok I couldn't fit the exact question in the title, so read carefully.
I want to wield a 2handed weapon in 2 hands, gaining the additional bonus to damage. While doing it, I want to fight defensively using Crane Style. So far so good, by itself, Crane Style does not require a free hand.
After I complete my set of attacks, I want to -as a free action- switch to a 1-handed stance, using Jotungrip. I'll take a -2 penalty on attack rolls, and won't get the bonus to damage for any AoOs I make during the round. However, I will now have a hand free to use Crane Wing.
First question: is this legal?
Second question: do I technically need Jotungrip to be able to do this?
Two handed weapons get 1.5x strength to damage, it's not really a "bonus" versus one-handed weapons which only get 1x strength. You can use a two-handed weapon with crane style no problem, you fight defensively and take your penalties to attack and get your bonuses to AC. No problems so far.
As your about to finish your turn after you've used you're full round action or your move and standard (or whatever combination of legal actions you're allowed to take) you can as a free action remove 1 hand from your two-handed weapon. Without some sort of special ability you are now just holding your two-handed weapon and not wielding it. Now, Jotungrip is an always on ability. You don't have to activate or deactivate it. So, if you have Jotungrip you could as a free action release the second hand from your weapon and continue to wield it with one hand with the penalties for using Jotungrip. Don't forget that penalties from Fighting Defensively apply to AoO that you make later in the round because it says "for the round" not for your turn. Once you're using Jotungrip the weapon counts as a one-handed weapon and you only get 1x strength. At this point, you could in fact use Crane Wing because you'll have a free hand. Just bear in mind you could use a longsword (or any one-handed weapon) in two hands and get the 1.5 strength damage and then release one hand as a free action to use Crane Wing and not need Jotungrip at all.
Summation: It's legal. You need Jotungrip to do it with a two-handed weapon, or you can do it with a one handed weapon wielded in both hands for the extra damage and not need Jotungrip.
On the AoO with Jotungrip, and Crane Wing, and two-handed weapon you would have -2 from Jotungrip and -2 from Fighting Defensively with Crane Wing, for -4 total.
On AoO with Crane Wing and a one-handed weapon (that had been wielded two handed but switch at end of turn) you only have a -2 from Fighting Defensively with Crane Wing.
Seems legit, though looks like you would need jotungrip and would have -4 to attack (-2 for jotungrip and -2 for fighting defensively).
Edit: what Claxon said
Thanks. Just to be absolutely clear though:
I wouldn't take -2 to attacks for using Jotungrip UNLESS I was making an AoO... right? My "normal" attacks on my initiative count would be fine..
If you're using a two-handed weapon with two hands then you're not utilizing the special ability granted by Jotungrip to wield a two-handed weapon in one hand, which means you wouldn't take the penalty either.
Assuming you use the weapon two handed during your full attack/standard attack then you wouldn't take the penalty then. If you do wield a two-handed weapon with one hand during your full/standard attack then you would have to be using Jotungrip (or another similar ability two use two-handed weapons in one hand) and would take any associated peanlty.
Nothing depends on making an AoO or not, it depends on how your wielding the weapon at the time you make the attack and if your utilizing the benefit of Jotungrip ability (which includes a penalty with it).