In Pathfinder, what are the rules for holding a two-handed weapon in one hand while using the other hand?

Question

I am currently GMing a Pathfinder game and the following situation came up: One of my players wanted to have his two-handed weapon held in his off-hand, while having a throwing weapon readied in his main hand. I told him that he was not allowed to do this because he cannot wield a two-handed weapon in one hand, but he technically is not wielding it. This brought up several scenarios which I will go over.

Before I begin, I hold the following to be true: Switching how your hands are used to hold weapons is considered Not an Action, unless doing so would require you to drop a weapon (a free action) or draw a weapon (move action).

The first scenario is moving with the two-handed weapon in the off-hand and a throwing weapon in the main-hand. I house ruled that he must take a non-stacking Medium encumbrance penalty while he is not gripping his two hander with both hands, as the weapon is cumbersome. He countered that a high strength character should be able to hold it without penalty, but I countered that it is the size of the creature holding the weapon and the weapons encumbrance (not its weight) in relation to the ability of the creature to manage it that determines this. A two handed weapon is just too awkward for a medium creature to hold without two hands. My understanding of the rules is that he should not be allowed to move at all unless the weapon is held in two hands or strapped on in some way, but I was giving him the benefit of the doubt. First question: Are there any RAW that specify whether or not moving is possible with a two-handed weapon held in one hand?

The second scenario is the same hand setups as the first, only he is throwing his weapon with his main hand while holding a two-handed weapon in one hand. I told him that he should take two-weapon fighting penalties for his ranged attack. Second question: Are there any RAW that specify whether or not you are allowed to make a ranged attack with a throwing weapon with a two handed weapon held in the off hand? Is it even possible to do that?

Lastly, the Quick Draw feat seems to allow you to switch weapons as a free action, which would reduce the need to try to do something like hold a two hander in one hand to squeeze an extra attack out, or have to options to attack with. It is the same mechanically (not thematically) as the above scenario, but fits into the rules.

Answer 1

Well, as you were asking from a RAW answer, here is from the FAQ:

Two-Handed Weapons: What kind of action is it to remove your hand from a two-handed weapon or re-grab it with both hands?

Both are free actions. For example, a wizard wielding a quarterstaff can let go of the weapon with one hand as a free action, cast a spell as a standard action, and grasp the weapon again with that hand as a free action; this means the wizard is still able to make attacks of opportunity with the weapon (which requires using two hands).

As with any free action, the GM may decide a reasonable limit to how many times per round you can release and re-grasp the weapon (one release and re-grasp per round is fair).

—Pathfinder Design Team, 03/01/13

Note the lack of penalties when having the two-handed weapon in one hand. Now to answer your questions:

Are there any RAW that specify whether or not moving is possible with a two-handed weapon held in one hand?

Nope, movement is affected mainly by armor. A wizard is able to run with his staff in one hand, and the game makes no difference in RAW between a quarterstaff and a greatsword, they are both considered two-handed weapons.

Are there any RAW that specify whether or not you are allowed to make a ranged attack with a throwing weapon with a two handed weapon held in the off hand? Is it even possible to do that?

Yep, as in above quote. Free action to switch the greatsword to one-hand, throw weapon as a standard action, free action to grab back the greatsword. Quick Draw would be helpful to draw the throwing weapon though.

Also, this question and other sources seem to indicate that Quick Draw can't be used to switch weapons as free actions.

Answer 2

Holding a two-handed weapon in one hand is perfectly fine. You can't wield it, so you're not threatening with it, but there's no problem holding a 2h weapon in one hand. It's routinely done with bows, polearmes, staves, etc. and I'm sure you've personally seen it done a dozen times. It's why bucklers exist for bow people, etc.

You will note the lack of rules to address this in Pathfinder as proof that this is operating as intended. Nothing anywhere says you can't hold/carry a two-handed weapon in one hand, to the limits of your encumbrance. Encumbrance is an abstraction, of course - you are welcome to bug your player by house ruling various restrictions, but IMO "you can't hold a two handed weapon just to carry it in an off hand" is a bad one. Many two-handers (esp. bowmen carry their two-handed weapon in one hand and a torch or something in the other till fights start.

You are welcome to house rule your game based on your own take on "realism" but RAW there is no penalty for any of this and it's legal.