Summon a bound sword as fast as you can while in combat. Put it away and summon again. Very fast leveling.
Go to a river and trigger one of the slaughterfish to attack. Step back to the bank so it can't attack you, and summon a bound sword over and over.
Works well for alteration, too.
Just make sure you don't have a follower with you.
Bound sword is how i do it too. I double fist 'em while running around mammoths and giants, ^the slaughter fish thing seems like a much easier way though.
If all you want is to level, rather than fish grind it up, why not just console commands. IMO, they are both equal cheats. It's not like you are really playing the game fakey fighting a fish.
Fully Perked Bound Swords, because You have Soul Trap, Turn Raised Undead, and Dispel Summoned Daedra. I can Dual Wield the Perked Bound Swords and level Conjuration to 100 before reaching Level 20.
Just keeping a Bound Sword in My characters Right Hand when using Flames to burn Opponents raises Conjuration. If My character is using a Flesh Spell, Alteration also goes up. Backing away from an Opponent and swinging at them can be used to fill Soul Gems, but having a high One Handed Skill is not considered to be Mage-like by Old Marry types.
Shalidor knows Mages tend to ignore Martial Skills, and leaves a Message in Game for Destruction Users.