[Underdark] Morphing Weapon Ability

[Tetsubo]

Underdark introduces a number of new weapon and armour magical
abilities. One of them is the Morphing weapon enhancement. It allows a
weapon to change into any other weapon of the same size category. So a
Medium One-handed weapon could become any other Medium One-handed weapon
as a standard action. So here's my question: Could a Large creature use
the example I just gave to create any Large Light weapon it wanted? Or a
Small creature use it to create any Small Two-handed weapon? Considering
the damage amounts of a Small Two-handed, Medium One-handed and a Large
Light weapon are similar, I don't think it would be unbalancing. Any
thoughts?

 

[Kae'Yoss]

I'd allow it. Look at the weapon equivalent variant rule: A medium longsword can be a small greatsword.

So if you are using this variant rule, you can safely use this change as well.