Calculating WDB for large creature wielding medium two-handed weapon

[Feldar]

A medium-sized creature wielding a two-handed weapon doubles Strength bonus to damage on a successful hit. Does the same apply to a large creature wielding a medium two-handed weapon in a single hand?

Citations please!

[hamishspence]

A medium-sized creature wielding a two-handed weapon doubles Strength bonus to damage on a successful hit.

1½ x Strength bonus, not 2x Strength bonus:


https://www.d20srd.org/srd/equipment/weapons.htm#lightOneHandedandTwoHandedMeleeWeapons

One-Handed
A one-handed weapon can be used in either the primary hand or the off hand. Add the wielder’s Strength bonus to damage rolls for melee attacks with a one-handed weapon if it’s used in the primary hand, or ½ his or her Strength bonus if it’s used in the off hand. If a one-handed weapon is wielded with two hands during melee combat, add 1½ times the character’s Strength bonus to damage rolls.




Two-Handed
Two hands are required to use a two-handed melee weapon effectively. Apply 1½ times the character’s Strength bonus to damage rolls for melee attacks with such a weapon.



Does the same apply to a large creature wielding a medium two-handed weapon in a single hand?


A two-handed weapon becomes a one-handed weapon when wielded by a creature one size larger than is appropriate for the weapon:


https://www.d20srd.org/srd/equipment/weapons.htm#weaponSize

Inappropriately Sized Weapons
A creature can’t make optimum use of a weapon that isn’t properly sized for it. A cumulative -2 penalty applies on attack rolls for each size category of difference between the size of its intended wielder and the size of its actual wielder. If the creature isn’t proficient with the weapon a -4 nonproficiency penalty also applies.

The measure of how much effort it takes to use a weapon (whether the weapon is designated as a light, one-handed, or two-handed weapon for a particular wielder) is altered by one step for each size category of difference between the wielder’s size and the size of the creature for which the weapon was designed. If a weapon’s designation would be changed to something other than light, one-handed, or two-handed by this alteration, the creature can’t wield the weapon at all.


So, if the weapon is now a one-handed weapon, and is being wielded in one hand, then it gets 1x Str bonus, not 1½ x Str bonus.

[Crake]

To put it simply, it's not the weapon being 2 handed that results in 1.5x strength modifier, it's the act of wielding with 2 hands that does so. You can wield a one handed weapon with two hands and get the 1.5x strength modifier as well (https://www.d20srd.org/srd/equipment/weapons.htm):

"If a one-handed weapon is wielded with two hands during melee combat, add 1½ times the character’s Strength bonus to damage rolls."

This does not apply to light weapons as their nature makes them difficult to wield with two hands and get your full weight behind the attack:

"Using two hands to wield a light weapon gives no advantage on damage; the Strength bonus applies as though the weapon were held in the wielder’s primary hand only."

If you could somehow wield a 2h weapon in one hand (monkey grip for example), you would still only get 1x strength modifier