I recently had my crafter create a weapon for use by another of my characters. The weapon had all the attributes I wanted but was left without enhancement so that this could be added as the character leveled. To add enhancement the forge in the UD was used. The following table shows the enhancement of the weapon versus the level required to wield it.
+5, 27
+6, 29
+7, 31
+8, 33
+9, 34
So, naively, adding another stone to give it a +10 enhancement should make it a weapon of roughly level 37? Wrong, it actually makes it level 43 and therefore unusable. There is nothing in place to prevent this happening and no clue that it might.
Would it be possible to make the forge "malfunction" with a message to the effect that the forge is "incapable of forging a weapon of such power" if increasing the enhancement value would take it above level 40?
Otherwise, at least this post might warn others of the non-linear scaling between enhancement and level requirements that can cause these sorts of problems.