[...]
Just because it’s not one sided if they duel doesn’t mean one isn’t far more powerful or flexible. [...]
Depending on the circumstances, they can be very dissimilar in power, sure. Place the Pure Fioghter in a hospital trying to save people, and he'll faiul utterly. In Combat, however, these three are somewhat equivalent, to the point that the various stats of the character are less relevant than how the characters are actually plaed. And what more balance can you want?
Hence why I suggested a fighter/magician or sorcerer since the additional offensive and defensive spells would make it more clear just how unbalanced your thought experiment is.
https://i.giphy.com/media/3o84sw9CmwYpAnRRni/giphy.webp
Nonetheless, a pure magic user with a 100 OB with a weapon is pretty difficult to attain even at 20th level, much less multiple weapons and a slew of combat maneuvers.
Yes, and a change of profession via such a spell is a way to achieve that abit more efficiently, but at the cost of never being such a good caster as the guy who did
not completely refocus is learning interests.
Moreover, your approach negates the need for semis altogether.
It does not, because the semi can do what the two pure forms cannot: Level both magic and arms within the same level. This will of course be most impactful when you are playing between levelling, as opposed to creating a 20th level character from the start. But even in the latter case, the center of gravity of his efficiency in learning is different than for any "purists" that change professions every other level or so.