Some people prefer more of a 'hybrid' build. Meaning to engage in melee while throwing out cones of colds and the like. However, many spells cannot be cast with a sword in your hand. If you try to do so, your character will sheathe the sword, then cast. This delays the casting and can cause a lot of trouble. There is a work around though. Use only one set of weapons, and when you want to cast a spell that requires your weapon to be sheathed then pause the game and "switch weapons". The result is that your character essentially sheathes his weapons instantly, removing the delay.