Can the Lightning Blade be used nonlethally?

[as91]

The Wu Jen has a small number of spells that create purely elemental weapons such as the spell Lightning Blade which creates a sword made out of lightning and does only electricity damage. Can it be used to attack nonlethally? I know that in general you cannot opt to attack nonlethally with spells like you can with weapons but it is a weapon. What if it were not created by a spell and was simply a sword made out of lightning? Would it doing elemental damage prevent it from being used nonlethally? I can't find any rules saying otherwise but it feels a little weird to me.

[Gruftzwerg]

Have a look at Complete Arcane page 85.

Weaponlike Spells
There it says that weaponlike spells do damage as spells and not as weapons.
And if it is not weapon damage, it doesn't have the permission to make use of "the rule for lethal weapons to do nonlethal damage".
This is even explicitly stated there that spell dmg can't be converted in either direction.
And it even says that if you wanna do that, that you would need the "Nonlethal Substitution" feat to do that.

[Powerdork]

My recommendation, if you truly wish to leave someone alive, is to simply mix in enough nonlethal damage from other methods (even risky ones like beating on them) that your lightning blade can't risk killing them in a critical hit, and they pass out when their HP falls below the amount of nonlethal damage you deal. If they take the attack of opportunity, consider that an acceptable cost. Or render them flat-footed somehow, so they can't take it.

[Eldonauran]

You want the "Nonlethal Substitution" metamagic feat from the Book of Exalted Deeds. You have to pick an energy type but all energy damage deal with that altered spell now does nonlethal energy damage.