Is there any limit to how much a Warshaper (Complete Warrior) can grow their limbs using their Morphic Weapons ability? As far as the rules say, it is possible for a Tiny creature to then grow to Colossal weapons with enough move actions.
Quoting the ability: (Emphasis mine)
I understand from the description that you can grow natural weapons according to the size of the shape you turn into, or if the shape you turned into already has natural weapons, you can enhance them to act as ONLY one size category larger. So I believe, that it's actually a matter of what kind of shape you chose to turn into, as the prestige class has a shapechanger type perequisite.
It totally depends on how you understand "the warshaper's form" :
I think the second option is what rules intended, but as they are written, nothing prevents you from using the first option.
Next questions are: can the increase in size of the natural weapon change creature's size ? What a kitty with a Colossal bite attack looks like ?
EDIT about the "as if" highlighted by @aslum's comment :
Although the ability says that a warshaper assuming a dire wolf shape may "grow his jaw and snout", it also says that only damage must be considered as if the weapon was one size bigger, so there's no real size augmentation, and a kitty with a Colossal bite attack just has the sharpest-est teeth ever. So the above questions are unfounded, but I leave them here.