Has everyone figured out their artifacts and such? You may want to include a quick description with your character sheets about their abilities, what the spirit weapon/shield is named, looks like, etc., and so forth. I'm trying my best to consolidate all this info in my own personal reference sheet, but I don't want to miss anything either.
Actually, the descript, I'm not having much issue with, but a weapon isn't so useful as I'd thought (so damn few proficiencies, and I'm hopefully never in combat anyways), and a shield bonus doesn't stack with the Shield spell, though can be drawn more often/faster. I'll probably make it a shield, deciding on what to replace my Shield spell with, since it's none too useful, so sort of part way there.
Actually, after I start seeing how people act in combat, weapon/shield items are going to have an effect even on magic. For instance, your spirit weapon could add to the damage dealt or affect damage type, improve the range, etc. A shield item could affect the duration of spells, add to your defenses, negate AoOs while casting spells, etc. Since they're more than just normal or even magic items, they affect your abilities in different ways. It may not have the same immediate payoff that a melee bruiser would get, but it will have an effect (melee combatants need some boost too anyway to keep up with casters, even if this is only a slight boost). Don't be too quick to pass up the weapon version (plus it can still be handy to have a weapon on hand if something happens to your ability to cast spells, or if you want to make an AoO or something- the weapon also doesn't have to just be a melee one, it could be ranged as well).
I just didn't want to give too much away all at once. These aren't normal magic items, and neither are they normal artifacts. In fact, I may have made a mistake in calling them artifacts to begin with.
As for stacking shield bonuses, it doesn't normally work as Thistle guessed, but I was looking for something both thematic and functional as a shield would be. I wanted it to affect touch ac and flatfooted ac appropriately, as well.
I could always just add a "Special:" line to my description saying it enhances the ability of shields and shield spells to protect the target, and stacks with other shield bonuses to AC despite the normal provision.
Do you guys think this is necessary? Do the casters plan on using Shield spells often enough for it to be an issue?