Sorcerer
In the land of Arthea magic has a tainted reputation. Wizardry struggles for self determination as a profession and those who practice magic, particularly in the northern kingdoms, are frowned upon. In their turn Wizards hold the intellectual high ground in their own speciality, and frown down upon Sorcerers. Sorcerers are supposedly those gifted individuals that can control magic without the mental disciplines gained by long hours of study spread over years. Sorcerers are often brash, confident individuals ready to sieze the power of magic and use it because they can clearly see how the magic works and is controlled.
These are the hedge wizards, the rebels and non-conformists with the world of magic. Regular wizardry teaches that this use of power is dangerous, that the risks to the individual are immense. And there is truth to this - there are very few old sorcerers. Magic that is understood not learned is the way for the Sorcerer, and this brings extra risk. Perhaps before the The Great Disaster, when magic was stronger, sorcerers were more powerful. Perhaps then they could exist without any reliance upon the organised world of magic. This is, sadly, no longer true. Now, despite their efforts to the contrary, sorcery needs at least a little of the knowledge that Wizards hold. To use the magic, they must observer the magic in action, or pull apart the spell incantations to find what is really going on.
Of course, this reliance only perpetuates the closed-shop nature of the circles of Wizardry. Using the excuse of 'keeping things secret' and 'protecting magic', Wizards actively engage in a process that keeps Sorcerer's at arms length from the core of magical knowledge. While this keeps sorcery alive with anger at the establishment, it also gives the only establishment that they rely upon. It is a sad and sorry state that sorcerers despise their mainstream counterparts yet at the same time are reliant upon them for access to the underlying methods of magic bound into each magical spell. And these are spells that the Sorcerers understand more readily than their Wizard colleagues.
The standard image of sorcerer in the Players Handbook outlines a free spirit, someone with command of the realms of magic by thought. This is still true in Arthea, the only significant change here is that to replicate a spell, the sorcerer must have a deep knowledge of its inner workings. This is straightforward for them to do; their class and level determines how many spells they can understand in this way. After all, sorcerer spells are really only a replication of the original, the actual power sources used and the protections placed to defend against mistakes may be different, even if only slightly. Their spells are carried out by intimately understanding the way magic works, not by learned knowledge.
The premise is that sorcerers can use magic because they have some innate ability to channel the energy and a whole heap of self belief that it's going to work. If their self belief crumbles, then all they can do is hope that someone finds enough bits to give them a suitable funeral.