Do offensive casting spells use the accuracy of the weapon equipped?  So if you have a feat that adds a bonus to wands then your spells are more accurate with a wand equipped than a bow?  Or a different example if you have a weapon that is enchanted to be more accurate will that also make your spells more accurate or is it only when using the weapon in weapon attacks?

They do not.

Only weapon attacks.

 

Medium and large shields however will reduce your spells' accuracy.

Thanks for the responses.