Tentative Fire Emblem Fates: Conquest ranks:
Corrin: After Draconic Hex, she doubles average speed (though it's not super-safe). Hits both defences, reasonably durable. Chances are you'll only have one turn with which to take her out, unless you're quite durable or have a faster, uncounterable 2HKO. Heavy
Felicia: Tough/dodgy against magic, but dies fast to physicals. Has a 4HKO, but at least it's of the 1-2 variety. We've seen this build before, adding Tomebreaker to it doesn't change it too much. Light/Middle.
Jakob: Knives are cool, he'll double the slow after hitting them with a Silver Dagger. Unfortunately, if he doesn't, his offence will be awful, and while it's 1-2, that just means he debuffs himself faster. Or makes his offence even worse. Light most likely, though Tomebreaker positions him well to defeat mages.
Elise: It's a similar stat build to Felicia, without Tomebreaker, but with one key difference: she doubles average! And hits a hell of a lot harder, a high 2HKO. Accuracy could be a bit better, but you still don't last long against her. The PDur is terrible though. Middle.
Silas: Nice physical durability, but the faster can double him. Damage is decent. Javelins/Hand Axes get him doubled for sure, so he really is up shit creek against mages. Light/Middle, but he does spoil melee fighters really well...
Arthur: Justice always wins! Great damage. He can often 2HKO with a Hand Axe followed by a Silver Axe, even, though Hand Axes leave him open to being doubled. He's pretty physically durable too. Middle
Effie: Wary Fighter means she won't be doubled, which is pretty great for her. Physically tanky, 2HKO damage, Javelins are a good option too. Middle, but a better one than Arthur... she does need her personal skill to match his damage, but she gets that against most people.
Mozu: Holy stat growths! Actually she doesn't have the best stat total anyway... but it's good enough. She just manages to double average, and Seal Strength means she'll be pretty physically durable after her opening hit. She can also set Life or Death and be very fragile, but have a shot at one-rounding average... only works on the slow though. Middle/Heavy.
Odin: His stats are all kinda vaguely below average (except Skl/Luck), which means he's much more physically durable than most mages, but the damage is a problem. Still, Nosferatu can push his durability further, or he can push for crits/vegeance with a forge, so he should make Middle.
Niles: Fast! Dodgy (if he isn't countering)! Magically durable! But... not very damaging. Has options for his counters, physical or magic, and doubling does make his damage less bad for sure, but it isn't 4HKOing average. If only he didn't have to choose between evasion and counters, or he had more than 0.67 pdur, I think he'd have a case for Heavy, but as is, Middle again!
Azura: Well she's almost OHKOed by average physicals, and isn't that much better against magic. She does double average but the lance rank stops her damage from doing much good. Light.
Nyx: Um well she's lucky that she has a skill to lower enemy evade, because otherwise her accuracy would fail. As is, she's another mage made of paper, but hey, Nosferatu heals almost half of her bad HP. She doubles the slow, and can hit them really hard as such! And Countercurse is nice against mages. But... I dunno, that pdur, and the accuracy can mess her up too. Light/Middle.
Camilla: Hits like a truck, and just misses doubling average by a hair. If you're slow, you're probably dead. If you're fast, you still have to deal with Hand Axe counter + Silver Axe 2HKOing average. Savage Blow makes for some nasty heal-locks, and her physical duraiblity's pretty good, plus Swordbreaker. Heavy.
Beruka: Hopes to fight someone slow so she isn't doubled. Trample and Savage Blow give her some pretty solid damage, so she can often 2HKO in practice, but against fast opponents she'll have a lot of trouble living that long. Fitting for an assassin, even if the class isn't. Light/Middle?
Selena: Speedy, enough to double average anyway. Decently physically durable. Can toss Hand Axes safely but not very effectively, just useful as an opening shot. Strength lets her down, though, but she still two-rounds average even if she can't counter. Middle.
Kaze: Doubles everything! Yes, I mean everything. Which means he two-rounds average at range 1-2 and has some modest evade, poison helps his offence further. Mediocre pdur, great mdur... Middle/Heavy area.
Laslow: Real bland, fairly average at everything in the end. He has a Hand Axe option but he'll get doubled with it a lot, so it's not a good one. As such ends up a largely pure melee type, which probably means Light/Middle. Healing procs could help but I don't respect them that much.
Peri: She 2HKOs average and may occasionally snag some doubles, or tilt fights with javelin counters. Not bad. Middle.
Benny: He's a total beast against physicals. Wary Fighter wards off doubles, like with Effie, so he's a pain in the ass to take down, even though his damage is only a meh 3HKO. Magic durability is actually respectable, so he can win some slugfests with that, but it's obviously still a big weakness. High Middle.
Charlotte: Doubles average. Game-best damage. Accuracy could be a bit better, but criticals make up for it. Give her a turn and she pumps out 140% OHKO damage (156% if you're female). Averagish durability and enemies fast enough to stop her from doubling are her weaknesses, but even then there are counters including Hand Axe ones. High Heavy. Probably Conquest's best dueller.
Leo: One of the best FE mage duellers ever. Leo's exceptionally tough against magic, especially after Seal Magic, counters everything, doesn't explode to physicals, and has the option of Nosferatu. Oh, and he can 2HKO while using it, because his magic rules. Unless he's doubled, that'll be hard to overcome. Heavy.
Keaton: He's weird, but certainly good. He has a high 3HKO which is usually a 2HKO thanks to Grisly Wound, which punishes opponents both when they attack (unless MT) and when he attacks them. He also regens 40% of his HP every other turn, and is very physically tanky. His weakness is the speedy double him, but he can switch weapons to avoid that, which makes his durability much more fair (physical still excellent). He feels like he won't lose much except to speedy mages and status, though that's certainly enough to keep him fair in Heavy.
Gunter: Frederick 2.0 pretty much. 4HKO damage (crappy ranged backup), doubled by everything, PDur is okay but MDur means any mage above Puny beats him pretty much. Light, probably worse than Azura.
Xander: Nice physical durability, ranged 1-2 counters, and he comes so close to a 2HKO. But... man, that magical durability. He's not too far from being one-rounded by mages (unless they're slow). Some sort of Middle, which is a shame because he's such a good PC.
Shura: Nifty. He doubles the slow, and can double quite a few more after he activates Highwayman, and has evade. The damage is a bit problematic though, especially if he doesn't double. Overall a worse Middle than Niles, but can still hang there due to the turn 2 evasion.
Flora: Well. If someone goes first and hits her with physicals she's probably dead. Otherwise she can try to debuff their speed and avoid being doubled, but honestly her damage is also bad, so she's not winning physical slugfests much of ever. Against mages, Tomebreaker sets her up better for sure. But, even Light mages are a problem for her with her damage, which means she's a bad Light herself.
Izana: And for our final dueller, a vanilla mage. Izana's speed is a bit problematic so fast fighters will wreck him, but he's got good magic durability, decent damage (almost a 2HKO), and wins plenty of slugfests when not doubled. Probably a Middle.