Ok, so my DM is running a campaign where arcane magic is at least heavily frowned upon, if not outright illegal, and psionics are the norm. As such, he's allowing a lot of stuff that may or may not be official. But here's the gist of my problem.
One class, the Soulknife, can create its own size appropriate weapons. Another, called an Aegis, has a similar mechanic for armor. And of course there's a prestige class that combines the two. At creation, a soulknife chooses whether they want to make light, one-handed, or two-handed weapons. They can pick up a skill to allow them to make any they want, but otherwise, at creation they're stuck with that choice. The aegis, through certain armor customization, can increase their size by two categories.
My plan is this. I want to make a Half-Giant, which get the racial Powerful Build, allowing them to use weapons one size-category higher than they are. With the Aegis class, I will be able to make myself Huge, thus enabling me to use Gargantuan Weapons. As a Soulknife, I can make weapons appropriate to my size.
Long story short, I need to know how to convert a Medium 2-handed weapon that does 2d6 dmg, into a Gargantuan Weapon.