I've noticed in several Magicka videos that you can enchant your weapon with magic, but I must have missed that in the tutorial. How can I apply magic to my blade?
Conjure up a spell, and Shift-Left Click. Then you can use it by doing Shift-Left Click without conjuring.
By the way: in general, if you use this method, the effect of the spell is cast in a straight line. For example, a shield spell will create a wall extending from your blade.