Arelith

I am not sure if it has been nerfed or its a bug but when this spell is cast on a summons like Shelgarn's persistent blade and Mordenkainen's sword it does nothing but give the weapon a elemental visual effects with no extra AB or elemental damage.
If Elemental Weapon is cast on a non magic weapon Henchman it to has the same result, the weapon gets the elemental visual effects and nothing else.

I have not tested greater weapon, Darkfire or keen edge if they to have the same bug.

Custom on hit effects presently only trigger for PCs, and Darkfire/Elemental Weapon use that script :)