Legendary Ryoma

Weapon: Raijinto (+Eff)

Assist: Reposition

Special: Noontime / Moonbow

Passive A: Atk/Spd Catch / Kestrel Stance 3 / Steady Posture 3 / Solo skills / Unity skills

Passive B: Bushido II

Passive C: Atk/Spd Rein 

Sacred Seal: Atk/Spd Solo / Mystic Boost / Spd/Res Solo / Equivalent Stances

• Ryoma's remixed base kit pushes him into the tried-and-true godsword build that's sort of become an overnight hit on other fast melee infantry units. Though much of listed skill combinations are rather standard, Ryoma has a couple of obvious and very significant differentiating factors.
  • Bushido II adds +7 damage for free on every hit, which tends to add up quickly especially in longer-winded matchups and helps him pick up the slack against more physically abled enemies. More importantly, however, it contributes significantly to this build's purpose by granting Dodge — that is, reducing damage by a maximum of 40% the faster Ryoma versus his current enemy — as well as nullifying his bow weakness (amongst other weapons) entirely. 
  • Raijinto provides distant countering, spectrum stats, and, most importantly of all, a compressed form of Null Follow-Up built into his weapon, giving him more ease against enemies with artificial follow-up skills. The last two effects require Ryoma to initiate or be nearby allies, the latter of which is a very common scenario when setting up carry unit positioning in Aether Raids anyway.
  • Ryoma's flier status affords him access to the Rein skill line — especially his new default Atk/Spd Rein which you'll find difficult to replace on a bulky offense hybrid build such as this one. Additionally, he has objectively superior movement options, allowing him to initiate and plonk in flier-traversable areas whereas infantry units are a little pickier with where they fight. 
• To improve longevity, Noontime allows Ryoma to heal on counterattacks at almost any moment's notice, and Mystic Boost in the Sacred Seal can also be taken regardless of Special as a reliable form of after-combat sustain. 
• The A-slot is pretty much free for any stat swing skills of your choice thanks to Raijinto's innate Distant Counter. 
  • Atk/Spd Catch is a bit rare at the moment, but if you can acquire it and abide by its conditions (preferably both), it provides a great dual-phase Atk/Spd swing with no positioning requirements like Atk/Spd Solo. 
  • High-tier Stance skills are also considerable given they provide Guard, another useful defensive tool this build can have in its arsenal. 
  • Finally, a Unity skill of your choice can act as a form of penalty reversion/negation, something that Ryoma unfortunately lacks in his high list of defensive effects. 
  • On a budget, you may stick with Ryoma's base Kestrel Stance 2 or inherit Spd/Res Solo or Spd/Res Form to increase his overall magic bulk instead.
• Much of what has been said for A-slots also applies to Sacred Seals, though Mystic Boost has already been discussed if you want Ryoma to heal more reliably in multiple tight fights.

Weapon: Firesweep S+ / Ninja Katana+ / Brave Sword+

Assist: Positional Assist

Special: Moonbow / Luna / Glimmer

Passive A: Life and Death / Swift Sparrow / Other Atk/Spd skills

Passive B: Bushido II

Passive C: Spd/Def Rein / Atk/Spd Rein

Sacred Seal: Life and Death / Heavy Blade / Other Atk/Spd Seals

• Already inherited the Firesweep Sword on Ryoma years before he finally decided to get good? No fret! You're pretty much in the same boat as a lot of other legendary Ryoma users, and fortunately enough, the weapon's aged well on him due to the great new offensive effect that Bushido II provides: dealing +7 damage on every hit. Taking into account that Firesweep Sword essentially deals free damage (as it prevents counterattacks), Ryoma can become a deadly player phase unit that is guaranteed to do at least 7-14 (if he doubles) damage per initiation. 
• Ninja Katana or its more accessible counterpart Brave Sword turns Ryoma into a pretty competitive Elincia substitution. They both massively benefit from the additional damage per hit from Bushido II, as they hit twice per strike and basically guarantees that at least 14 damage will be dealt, and even upwards of a deadly 28 if Ryoma follows up and makes a quadruple attack.
• The choice between the Brave weapons and Firesweep Sword ultimately depend on whether you prefer larger damage output in a single strike versus safely in attacking. 
• As this build basically operates in player phase exclusively, the purpose behind other skill slots are quite obvious: build up Ryoma's offensive potential as highly as possible.
  • Life and Death, in particular, make a great A-slot and Sacred Seal choice. As the weapons mentioned in this build offer some form of safety in attack — such as preventing counterattacks or simply dealing huge blitz damage to the enemy before they can do anything — the defense drops from Life and Death simply don't matter most of the time. If Ryoma absolutely must take a hit with his reduced defenses, Bushido II's damage reduction effect also typically serves as an emergency button in such situations. Else, you can run other skills of the Atk/Spd-boosting variety, with Swift Sparrow being a somewhat more common option than others. 
  • Spd/Def Rein hits all the right spots as far as improving Ryoma's damage and follow-ups are concerned. However, Atk/Spd Rein is a fine C-slot default despite not impacting Ryoma's damage directly — it's preferred when using Heavy Blade, which will be required to activate Moonbow or Glimmer in one sitting but requires Ryoma's Attack to be comparatively higher than his enemy's. 
  • Lacking the cooldown acceleration of Heavy Blade or simply preferring a higher damage Special, Luna is a valid Special choice over a 2 CD Special.