I'm playing a wizard in a D&D 3.5 campaign and I normally use the "shocking grasp" spell with unarmed attack (basically, touching the target). Occasionally tough were encounter enemies that it's not a good idea to touch (like lava creatures). The spell description simply says:
Your successful melee touch attack deals 1d6 points of electricity damage per caster level (maximum 5d6).
Where "touch attack" doesn't actually mean unarmed attack, but against what type of AC the attack is made. Also, while I can't find a reference in the player's rule book at the moment, it is acceptable in our campaign that a spell caster using such a spell can "hold the charge" (until an attack hits or the caster dismisses the spell, the caster can continue to attempt to deliver the spell).
It was suggested that the caster can deliver a shocking grasp spell using a simple metal weapon - such as a dagger - instead of doing an unarmed attack.
It's a bit more complicated because I'd need to cast, draw the weapon then attack - total of two standard actions and one move action, which will require 2 rounds, but is there a reason it wouldn't work - according to the rules, common sense or any other reason?