There's a prep that gives shocking touch that doesn't seem to give shocking touch damage for claw attack (this is when I'm wielding a spear - same thing with axe). See below.

Your defensive spin deflects Guktuka the Matriarch of the Brood's pound.
Your defensive spin deflects Guktuka the Matriarch of the Brood's pound.
Your thrust *** DEMOLISHES *** Guktuka the Matriarch of the Brood!
Your shocking touch scratches Guktuka the Matriarch of the Brood.
Your thrust *** DEMOLISHES *** Guktuka the Matriarch of the Brood!

But when I remove the spear, I get shocking touch damage (this is with no weapons). See below.

You parry a glauruk conscript's thrust.
You dodge a glauruk conscript's thrust.
Your shocking touch *** DEVASTATES *** a glauruk conscript!
A glauruk conscript is DEAD!!

Seems that shocking touch only applies to primary weapon not dual handed. Bug?

Invoker touch spells require you be unarmed.

EDITED since I missed you shocking while wielding:
Looks like the damage varies while off-hand shocking. It's less than if main-hand shocking.
I'm okay with that since you're getting to change your damage type.