World War Witches

Numerous anime titles over the years have to some degree dealt with the militarization of magic, with Fullmetal Alchemist, Strike Witches, and The Legend of the Legendary Heroes being prominent examples. The past two seasons have seen a cluster of such titles from a peculiar subset: the flying witch in a World War-like European setting on an alternate Earth. Each represents a distinctly different approach to the concept, too.

Air Offense/Defense

In Brave Witches the witches are essentially anthropomorphized WW2-era fighter planes when they don their Striker units; they even carry weaponry similar to their modeled plane and their Striker units duplicate the plane's distinctive engine sounds. Magic is used primarily for defense, to power their Striker units to enable flight, and to supplement their physical attributes, although each witch also has some ability beyond that. Because the witches are all on the same side, there are never head-to-head witch battles beyond training exercises.

Specialized Striker

Izetta: The Last Witch instead casts its witches as elite strikers wholly independent from any other military unit or role; in fact, a recurring theme is how the emergence of Izetta (and later Sophie) on the battlefield totally upends traditional military tactics. They can outmaneuver fighter planes in flight, manipulate weapons to turn them into guided missiles, power primitive rockets, even use their blood to create ice weapons. One can single-handedly decimate an enemy battalion on the battlefield, and when they meet head-to-head, watch out! However, these witches are extremely rare commodities which are cast as out-of-place in the era in which they fight.

Air Support (and later Mobile Offense)

Okay, so Tanya from Saga of Tanya the Evil isn't technically a witch, but given her abilities and disposition, she might as well be, right? The magic-users of her setting supplement established WWI-era military roles rather than outright replacing them. They are effective as artillery spotters and ground support and can take a primary offensive role against opponents with limited or no air defense, but regular planes still have a place because (except for Tanya) mages have a distinctly lower altitude ceiling than planes do. Mage-on-mage combat is a frequent occurrence and typically plays out akin to ground-based combat between elite troops. Later in the series mages are reimagined as a primary offensive strike force while ground units play defense.

But Who Would Win?

All of this begs an obvious question: who would win if the magic-users from each group could go head-to-head in the skies above a hypothetical neutral world? First let's consider the group-vs.-group option.

502nd Joint Fighter Wing vs. Imperial Army 203rd Air Mage Battalion

Except possibly for Tanya, the 502nd would seem to have a distinct speed advantage since they are based on WW2-era planes, which make any aircraft from the early 1920s obsolete by comparison. This exercise is more interesting if we ignore that, though, so let's look at their capabilities otherwise. Both units are well-trained and seem to have good morale, so it's a wash there. Both are capable of using magical shields for defense and primarily rely on mundane weaponry (albeit with magical enhancement) as the core of their offense, so that's also a stand-off. The advantage goes to the 502nd for a higher altitude ceiling (except for Tanya), but two factors not only balance this out but also push this battle decidedly in favor of the 203rd: the mages of the 203rd are much more trained and oriented towards fighting other magic-users and Tanya's most potent magical strikes can simply overwhelm the 502nd.

Mano-a-Mano

Putting Tanya up against any member of the 502nd isn't even a contest. Take your pick of that lot and Tanya would annihilate her, as she outclasses any of them enough on power, cunning, and ruthlessness to make any speed disadvantage negligible. Likewise, I can't imagine that any of them would fare well against Izetta if the ley lines that Izetta depends on aren't an issue, especially if she has her witch-empowering gemstone. Izetta's ability to simultaneously attack from multiple directions could negate the defenses of 502nd members.

So that leaves Izetta vs. Tanya, which makes for a truly epic match-up. Both are extremely nimble in the skies, and Izetta's cleverness and adaptability in a fight can offset Tanya's tactical acumen. Tanya can generate magical shields, but Izetta can manipulate objects as shields. Izetta can manipulate multiple objects at once to potentially attack from multiple directions, but Tanya's gem allows her multi-shot capability with the approximate equivalent of a computer-guided targeting system. Both can toss off really powerful magical effects, too, although Izetta's seem more costly to use.

Ultimately who would win such a duel comes down to the circumstances. If Izetta doesn't have her magic stone or has to worry about ley lines then she's outclassed, period. Even if those factors aren't against her, Tanya's ruthlessness would seem to give her the advantage. However, her self-interest is so strong that I can't see her standing in a fight-to-the-death situation to the point of mutual defeat. Izetta, on the other hand, would do that if it was for Finé. Hence I see a win for Izetta if she has a powerful enough reason to fight to the death, but a win for Tanya otherwise.