First off please forgive any formatting issues as I am writing this on my phone.
So the thought I had was to make a Spellcrafting skill line with one active ability much like armor lines. The passives would be a combination of passives similar to the passives you might find in weapon skill lines and/or crafting lines.
What exactly would you craft? Well you would craft a spell or magical orb like item that would take a 1-h item slot. The item would be crafted in a way similar to enchanting or alchemy where you would provide a combination of items to design a spell with up to 3 traits. The active ability on the skill line would then effectively cast a spell defined by the orb you hold.
Traits could be things like damage types, control effects, AOE or Range modifiers, etc.
I have more in mind but this is the general idea of what I was imagining that might actually be a good compromise that both implements spell crafting as well as a 1-handed magical weapon in while also not requiring a redesign of the entire class system because only the spell crafting active ability would be affected.
Thoughts?