[Mathias]

Here's a change I had to make for the Pathfinder version of the sawtooth sabre that I haven't gotten into d20 yet:

So, you can see the test for whether it's a custom/magic weapon, and then the alterations to the real thing. The same methods would apply to armor, as well.

 
~ If we have exotic weapon proficiency for this weapon, we're Light
if (tagis[Helper.ExoticProf] <> 0) then
  perform delete[wClass.OneHanded]
  perform assign[wClass.Light]
  endif
~if we're a custom/magic weapon, we need to alter our parent, too
if (container.ishero = 0) then
  if (container.parent.tagis[Helper.ExoticProf] <> 0) then
    perform container.parent.delete[wClass.OneHanded]
    perform container.parent.assign[wClass.Light]
    endif
  endif