...this is incorrect. you cannot by rule use a large great sword, the archtpe does not allow you to wield one. all it does it reduce the penalities if you were able to wield one, but since by rule you can't, it has no effect, because it does overule that rule, it only lessens the penalies if you could wield such weapons. hence all it doeshere is what i got from it.
Jotungrip (Ex): At 2nd level, a titan mauler may choose to wield a two-handed weapon in one hand with a –2 penalty on attack rolls while doing so. The weapon must be appropriately sized for her, and it is treated as one-handed when determining the effect of Power Attack, Strength bonus to damage, and the like. This ability replaces uncanny dodge.
with this a M character could use a M greatsword with one hand.
the only reason i could see this is if someone wanted to use the greatsword with a shield...Massive Weapons (Ex): At 3rd level, a titan mauler becomes skilled in the use of massive weapons looted from her titanic foes. The attack roll penalty for using weapons too large for her size is reduced by 1, and this reduction increases by 1 for every three levels beyond 3rd (to a minimum of 0). This ability replaces trap sense
With this a M character could use a L Greatsword with 2 hands. and i dont think its limited to just large.
PS. im guessing the looted part is just for flavor but you can simply ask your DM i dont see anything along the lines of "They must be looted"
also if you want to use both then carry a great sword your size and a greatsword 1 size larger and decide which one to use.
your size = 1 handed larger = 2 handed
your not looking for an eather or wep its a bigger or your size wep because Jotungrip says the wep must me your size to do this and a large bastard sword is not a M characters size.
its pretty much show off by using a greatsword like a longsword at -2 or use a big ass greatsword like a greatsword
ahh i see it now my mistake. and they will probibly fix this At at some point because i really think its intention was to make it so people can make that anime character with the 100lb blade of death. it seems like something a dm can hand wave or make over complicated. because even with the large bastard sword you would still need a M one for J grip which if you wanted to do that you can just take a feat on a different barb...
yup it has been discussed to death
a large bastard sword is lare enough weiing almost half what you can carry in total its quite large!!