I was curious if there is a common convention around mutants with Gigantism and the damage that their weapons yield. The damage bonus obviously is meant to augment their size, but it feels like a 20' tall humanoid should be able to wield a bigger weapon and have better reach (albeit reach doesn't really come into the rules) than a standard sized mutant. I was thinking about just using a stepwise system where each increment of bonus to damage also is an upward step in the damage die in the mutants arsenal. Each increase in size (of weapon) would also double the price of said weapon.
d4 --> d6 --> d8 --> d10 --> d12 --> 2d8 --> 3d6
So... a 20' tall human's longsword would do 2d8 damage. I guess if I did this I would ignore the damage bonus (since both are achieving the same net effect).
I think a balancing side-effect would be that they be a lot easier to hit. Maybe the damage bonus, should become an AC penalty.
What have other people done?