Second Age Legion

The Legions of the first age were much larger and more capably commanded by the Celestial Exalted, with the usurpation, logistics of having such large armies under a single general became nightmarish and their size has dwindled to half of their former glory. 

Legion

A legion consists of the following;
10 dragons - 6271 Soldiers who are split into various groups to make up skirmishers, engineering corps and archers, though many have dual roles in the army, most are not exalted and aren't able to easily switch from ranged attacker to melee skirmisher.
Baggage train can be excessive with such a large force in order to house and feed them on the move, though they will also continue to provide supply lines to the nearest settlement that the army holds sway with.
The Legion is headed by a General who commands through his subordinates, this was much more easily handled in the first age with the magics of the Solars.

Dragon

A Dragon Consists of the Following;
2 Wings - 627 Soldiers including the command structure
Command Structure;

• 1 Dragonlord
• 2 Winglords
• 4 Talonlords
• 20 Scalelords
• 100 Fanglords

Wing

A Wing consists of the following;
2 Talons - 313 Soldiers including the command structure
Command Structure;

• 1 Talonlord
• 2 Talonlords
• 10 Scalelords
• 50 Fanglords

Wing (Company-ish): 2 talons (250 infantry), commanded by a major (Winglord; no Roman equivalent) (313) Talon (Company): 5 scales (125 infantry), commanded by a captain (Talonlord; Centurion) (156) Scale (Platoon): 5 fangs (25 infantry), commanded by a lieutenant (Scalelord; no Roman equivalent) (31) Fang (File, Squad): 5 infantry, commanded by a sergeant (Fanglord or Fangleader; Principales) (6)

Legion

While Legions are roughly 5,000 soldiers (including all the logistics) with their commanders they come closer to just over 6,000 personnel.