First off, a Sorcerer never has to prepare spells. But only 6 spells for each level of spells. This means if you use 1 level 1 spell, then you have 5 left to choose from that remain in the level 1 category. A pure Mage (not specialized) is the best magic user in the game. Learns every spell there is, and can apply them if he prepares them beforhand. A dual-classed Mage depends on the Mage level to determine power. If you got the Mage level high enough that they know all the level 9 spells their gonna know, then yes, dual to a fighter or thief. It will only make you stronger
