I've been evaluating the 1-handed sword characters some more and still end up with Millay having the most utility--so I would. She, Paula, and Ameria are very similar in "features" (pipe down, I'm not talking about looks!): high SKL growth (3 rune slots by max level, high MP, good accuracy), high base MOV (all 6), Extra Move, Godspeed (all MOV=7 with Godspeed and 10 on a Kangacorn w/Godspeed), Bull's Eye for even better accuracy
-Millay can use a shield, which generally gives superior defense and some stat bonus (STR or SPD)
-Millay has a STR growth of A while Ameria and Paula have B
-Millay is in 2 unites. The Obel Soldiers attack involves Jeremy and Trishtan, and by the time you get Jeremy and Millay, you've probably been enjoying Trishtan's great early-game stats, and both Trishtan and Jeremy are pretty good early to mid-game. Her other unite is the Nymph Attack with Corselia and Rita. Rita is not very useful, but you can switch her in when you want the unite (although they take a long time to recharge). Paula has 1 unite but requires the Razril gang Keneth, Tal, and Jewel, so that's a lot of commitment to the roster and forces you to make space for 3 other 1-handed sword users--it's very impractical, and Tal and Jewel are definitely lacking in usefulness. Ameria has no unites--she's so lonely..
-Millay has more element options, mainly because there's the useful Wing Mail, and there isn't any equipment to change someone to Fire.
-Millay and Ameria have the Critical Hit skill while Paula doesn't
-Ameria has significantly more HP with a growth of A, while Millay and Paula have C. early on this could be an issue, but you're given plenty of equipment and the Switch ability to avoid bad situations for low HP characters.
-Ameria and Paula have better MAG, but it has limited use on fighters-- only extra flat damage on Magic Sword.
I still think Snowe is one of the best with his turn frequency (SS in Speed Growth with extra growth after lv 30, A in STR, S in SKL), but because he doesn't have Extra Move, he has limitations. You can't start from a distance away on a Kangacorn, ram through the target and retreat safely with him, so he needs more thought into how he can be used safely.
The other male 1-h sword users worth noting are Trishtan, Jeremy, and Keneth, but they're hardly on the levels of the other 4 characters mentioned above.
Trishtan is extremely useful early and still useful mid-game, but his poor stat growth in SKL and his SPD tapers off, leaving him somewhat average mid-game and easily below average late game, when he simply doesn't have anything going for him besides being tanky.
Jeremy and Keneth are pretty similar: Jeremy edges out Keneth with superior SKL (Keneth is not likely to get 3 rune slots) and MOV, but early on they are about equal, and Keneth's ability to equip shields gives him a marginal advantage. Late game, you might prefer Jeremy's 3 rune slots and higher MP, but he's kind of slow. Keneth's unite with Katarina is also more useful than the Obel Soldier Unite (Jeremy, Millay, Trishtan) simply because you can use Katarina, a mobile mage, instead of 2 other 1-handed swordsmen.