Dragon Emblem

I find dragon-centered teams to be incredibly unreliable when it comes to arena defense. As you can see yourself, all your dragons have an enemy phase build, which can be easily abused by just baiting them into a color-disadvantage matchup, because almost all the steady breath dragons (with a few exceptions) have horrible player phase potential. Also you don't have any surprise mechanics, because dragons are so static and can't really catch people off guard, because they can't do any wings of mercy + powerful mage nuke or dancer combo (ok, I know that Ninian exists).

If you are building purely for arena offense, where you can actually utilize their enemy phase and synergy, then yeah, sure, but be careful about putting them on arena defense. I find that dragons are best on infantry or mixed teams, where they serve as enemy phase safeguards.

With that said, there is not much to change in your team. They all do the same thing, but have a different color, while Tiki also has a more unique weapon. Swordbreaker might be a better idea on Nowi than on Tiki tho.

I would check out these guides when making an arena defense team and a dragon team:
https://fireemblem.gamepress.gg/general-team-building-guide-arena-defense
https://fireemblem.gamepress.gg/dragonborns-guide-dragon-teams
https://fireemblem.gamepress.gg/how-use-dragon-team

Hope you find what you’re looking for. :)

Nowi or Tiki can both handle Falchions if built for it, but if you wanted to try something different for Tiki, maybe try her with heavy blade. Atk/Def bond, QR, Ignis/Aether. Pretty similar to SB tbh except she has a better player phase if she can one-shot. But that's also if she can position for max attack buffs.

Nowi can go Swordbreaker + deflect melee as a dedicated Falchion check. Or if you're not worried about Alm, QR seal is good for non-sword matchups.

Just some ideas. As someone who also uses Nowi+Tiki on my main team, in my experience Nowi can usually handle Falchions fine without Swordbreaker as long as she has enough defensive buffs (through CD3/steady breath/rallies/spurs).

You have very similar ideas to mine on how to build a dragon core. I agree with your IV choices except for Fae, but if you're using bowbreaker then that IV makes sense. I think the most solid option for Fae is to use SB, QR, and DD and just accept getting doubled, so +def -HP and refine her breath for def. Her ranged def is 39/36, which I think - not having calculated - is usually enough against B.Lyn, including quad build. It might not be enough against fast green mages, though, so you'll want to take that into consideration. With bowbreaker and focusing on res, the occasional Sothe/Kagero can cause some serious issues unless your strategy is just to count them as so small a minority that you'll just lose to them and win the rest.

A.Tiki +atk is a very good option with her prf; OHKO against lots of enemy dragons. I think I prefer guard + QR for her, but QR + deflect magic might also be good. Guard + QR is probably more solid than QR+close def in arena because of bold fighter. And I would go with steady breath so that she can build up a big special if she gets hit with anything ranged, which is almost certainly going to double her. For arena, ignis is probably best unless you want to have a try at taking on multiple opponents. Swordbreaker, I preferred Nowi at first, but A.Tiki is fine with it. You will need to initiate against bold fighter swords (otherwise bold fighter cancels with swordbreaker and they double anyways because Tiki is slow, and the black luna / whatever will probably win); slaying axe + bold fighter + ignis she can actually bait because she has 44 def so the ignis is going to be the only damage she takes unless they have 56+ atk, and even then they can barely scratch her. Dragon fang + heavy blade Raven/Linus might be an issue; they'll hit twice for no more than 7-8 damage but the dragon fang is good for around 25 extra damage, which might be enough? Bold fighter L.Hector will also be an issue unless you can find a way to get through him in one hit. Maybe atk/def bond needs to be reconsidered if you want swordbreaker A.Tiki.

Nowi should use +spd breath and get spd buffs if she wants to go this route. Otherwise I'd leave her spd as it is and just focus on def. I would consider swordbreaker + QR on her. If you run into Alm you don't want to let him initiate, so either Nowi or A.Tiki needs to use swordbreaker or you need to get ready to really compete hard. (With QR, you can block a double from any non-Alm Falchion and double back. You probably will take a hit from a Falchion even with swordbreaker.) Ja, swordbreaker is nice because you screw the firesweepers too; otherwise it's quite hard to find a double against them and they often build to survive one hit.

The trouble is that now both A.Tiki and Nowi want the QR seal. I don't know what can be done about it.