Emblems Edelgard/Dimitri/Claude (VA: Ai Kakuma, Kaito Ishikawa and Toshiyuki Toyonaga), known as the Emblems of the Three Houses, are three Emblems that reside in a single bracelet.
Similar to Eirika who shares with Ephraim, the three House Leaders all occupy the same slot/bracelet. Internally, they are probably listed as Edelgard.
When synced with Emblems Edelgard/Dimitri/Claude, one of the three is randomly selected during each turn. Their Sync skill “Lineage” grants 120% experience gain.
More precisely, their Sync skill “Friendly Rivalry” is what triggers the rotation.
Anyway, they’re fighting at Firene Castle, training against some Firenese soldiers. Nothing too special, but Alear has the Wille Granz sword. Also, when Engaged with Edelgard, Alear can use Dimitri’s Areadbhar. So weapon-wise, it doesn’t seem to matter which House Leader is currently active.
Emblem Edelgard’s Sync skill “Flame Gambit” places flames on the opponent and the surrounding squares after combat.
Full name is Gambit: Raging Flames, based on Three Houses.
Emblem Dimitri’s Sync skill “Shield Gambit” nullifies the first hit when attacked from 2 or more squares away, for one turn. This could be handy when facing down archers, for example.
Full name is Gambit: Sacred Shield.
They’ve moved to the Brodia Castle map, presumably training against Brodian soldiers. Timerra has Brionac in her inventory.
Emblem Claude’s Sync skill “Arrow Gambit” inflicts poison on the opponent and foes within 1 square of the opponent after combat.
Full name is Gambit: Poisoned Arrows.
Here’s the Brodia/Elusia border fortress map. Etie triggers Bow Focus Level 1.
Aymr is an Engage weapon belonging to Emblems Edelgard/Dimitri/Claude that can Smash foes and inflict massive damage against Dragons.
Lapis is Engaged with Claude while using Aymr. She also has Georgios, a S Rank blade, plus Caladbolg in her inventory. Aymr is a “heavy” weapon that can inflict Smash. When initiating combat, the user goes last and cannot follow up, but the impact knocks the foe back 1 square.
“Combat Arts” is an Engage skill belonging to Emblems Edelgard/Dimitri/Claude that allows you to consume Engage turns to use one of Edelgard, Dimitri or Claude’s special attacks via the “Combat Arts” command.
Goldmary is at the Solmic camp during night. She uses Edelgard’s Raging Storm, which costs 3 Engage turns. It allows the user to act again after combat, like in Three Houses.
Likewise, Dimitri and Claude’s combat arts are Atrocity and Fallen Star. Presumably they have similar effects to Three Houses (bonus damage versus all foes and avoid all attacks during next combat).
Finally, their Engage attack:
“Houses Unite” is an Engage Attack that Emblems Edelgard/Dimitri/Claude can use, which triggers three consecutive hits using the Aymr axe, Areadbhar lance and Failnaught bow.
Seadall is Engaged with Edelgard at Tea-Field Village. Since this attack uses an axe and lance, it can Break lance and sword users.