It's a hard question to answer without understanding an individual's (either the OP's or anyone who wishes to answer) paradigm around the balance between magic and "mundane" (martial) characters. Kinda gets back to what
@Umbran was saying.
It depends where your understanding & concern lies. For example, you might have at the forefront of your mind –
Fireball is way more powerful of an area effect than martial characters lacking magic can muster, and that creates narrative dissonance around my fantasy of Conan cleaving through hordes of monsters. – And that will send you down certain directions of design tweaking, whether it's downgrading certain spells, reintroducing AD&D-style multiple attacks against weaker foes, introducing 4e-style Minions, etc, etc.
Alternately, you might have at the forefront of your mind –
The problem is that certain magic abilities empowering exploration, like Teleporting or Flight, have no equivalent for martial characters lacking magic. One can reach the flying dragon or the flying citadel, and the other cannot and must rely on their friend. – And you can tackle that issue in multiple ways depending on where your focus is:
(A) Give the martial character an ability to shoot dragons out of the sky (like "Heroes" in OD&D/Chainmail could). A "Taunt" would fulfill a similar idea of bringing the unreachable enemy to you.
(B) Give the martial character an ability to do Super Jumps, modeling a more mythic or anime style of game.
(C) Give the martial character broad-reaching Plot Points that allow for reasonable explanations of how they get there – addressing a multitude of potential concerns with one abstract mechanic like
@Stalker0 suggested from the Buffy RPG.
(D) Let the disparity remain, but ensure there are OTHER disparities that requires the Magic characters to rely on the Martial characters instead. So they mutually rely on each other.
Then there's points of contention, where maybe one person thinks that (D) mutual reliance is already present in the game, whereas another thinks it absolutely isn't, and another who thinks it is imbalanced but revels in the imbalance.
I think the deceptively simple one-liner presentation of the question is unintentionally obscuring a more complicated conversation. Which honestly has tended to devolve into circular arguments, so I understand wanting to skirt around that.
