I am quite aware that Powerful Build isn't in the Pathfinder world, but from playing 3.5 and using the ability my group has allowed it in Pathfinder. Simply adjust the +4 size bonus to +1 for CMB/CMD, and everything else pretty much fits.
Now that I got that out of the way, here is my question, which I never thought of in 3.5.
If a medium sized creature has the Powerful Build feature, which allows them to hold a medium sized greatsword in one hand (I believe with no penalty) and a large sized greatsword two-handed, then could they hold a Medium Two-handed reach weapon in one hand and apply reach still?
I am playing a Fighter that has a efficent quiver, and want something so I can grab a longspear or something of the sorts and make CMB attacks at a distance from not investing in the feats. Also, I am right to assume with an efficient quiver I may as a free action (just like grabbing ammunition) take out a long spear and if I please put it away as a free action too?
Inappropriately sized weapons and reach are a gray RAW area. Same example without 'Powerful-Build' is a medium creature that uses a small two handed reach weapon in one hand.
Is it legal by RAW? Following the Inappropriately Sized Weapons RAW i would say yes but on my table you lose the reach ability if you use such a weapon. I think that should be RAW.
Drawing is a free action but putting away is a move equivalent action.
@Ughbash, nothing was being confused about the range being affected like that, but I do appreciate you going out of your way to write those details anyways. My focus is on the question of using a reach weapon of medium size in one hand, and still retain the reach, which your answer is "yes".
Mechanically, this would seem to work. However, I think DM intervention is required here. Powerful build, coming in from 3.5 where reach is calculated differently, needs to be altered to fit ALL pathfinder mechanics, not just combat crunch numbers such as size bonus or CMB/CMD. The reach quality must be examined for functionality.
A longspear still can't be wielded properly just because you have large muscles. Try holding a very long stick with one hand at the very end of the grip, and hold your arm perpendicular to the ground. Does the tip start falling towards the ground? Of course it does. It will regardless of your build size. If you choke up on the weapon to wield it properly, you will lose reach.
Unless you have specific training in using that kind of weapon, such as the Phalanx Soldier does, your effective reach may be compromised.
So it's up to your DM as to whether that weapon retains or loses its' reach property or not.
The argument isn't much different from the common one I've seen made that a medium person can wield a small sized longspear in one hand, pay the inappropriate size penalty on attack rolls, and have a 1-handed reach weapon.
I don't have a problem with it, myself. All the other styles of combat, whether you choose to use that other hand for TWF, for a shield, or nothing at all -- are underpowered compared to 2H fighting anyway.
But a lot of people go nuts about it.
Disclaimer: I've never attempted to do it myself and don't think I ever will; please don't lob insults at me about it as if I have a stake in it.
Half-Giant is the psionic race with powerful build, actually. Just like in 3E. Goliath is a 3E race that also had it. I don't think it's been republished for PF by 3rd parties yet. Probably due to copyright.
About one-handed reach weapon : The phalanx soldier fighter archetype seam being able to use polearm of his size one-handed without penalty, but at the restriction of wielding a shield.
Phalanx Fighting (Ex)
At 3rd level, when a phalanx soldier wields a shield, he can use any polearm or spear of his size as a one-handed weapon.
This ability replaces Armor Training 1.
I think that powerful build shouldn't allow to emulate this ability. Personally, I houseruled that ability such powerful build makes that large weapon are appropriates for your size, but not medium ones. So, you can wield a large long sword one-handed, but not a medium two-handed sword without penalty. So, if your goliath want to have a one-handed long spear, he must suffers the normal penalties for inappropriate weapon size (big hands, little shaft).
Powerful Build only treats you as size large when it would be beneficial to you.
Powerful Build in 3.5 did allow you to hold lage size weapons without penalty, and allowed you to hold a greatsword of medium size one handed. I never thought of the concept to use a two-handed reach weapon of medium sized one handed before to gain the benefits of reach, which is why I'm asking.
To clarify once again, there is no misunderstanding of the reach rules in according to size. It is very well understood the limitations of the fact that you're still a medium sized creature and not a large.
Two-handed Medium weapon into a one handed weapon acts as a large one handed reach weapon, which would leave this option eligible, right?
There isn't RAW on powerful build which is obviously why I am asking for others insight, and the Phalanx fighter being mentioned really does help. I can't really imagine some weapons like a scythe being used one handed under almost any circumstances, but that special training mentioned for Phalanx could be to use a reasonably shaped weapon (spear or polearm) that should be a large one handed weapon, which I don't see as a farcry from what the Goliath (Powerful Build) can do naturally.
So my two cents so far are that as long as the flavor of the weapon makes sense in terms of it being operational in one hand, then it should be good. My GM doesn't want to deal with unforeseen issues, and my character just running up with an efficient quiver full of polearms in order to get a no AoO reach CMB attempt, while still holding my bow. I suppose I will carry a whip and suffer the -4 penalty and keep myself at most 15 feet away.
In 3.5 there was a Sword-bow magic item-- which could switch back and forth at will in the middle of a set of attacks even.
I know such a thing doesn't exist, but you could possibly get a friendly wizard to build a polearm-bow?