The Three Regalia are the three legendary weapons claimed by King Adrah when he founded the kingdom of Archanea. They are the fire bow Parthia, the lance Gradivus, and the sword Mercurius. The Regalia have effects when used as items. Gradivus restores the user's HP, and Parthia raises the user's Resistance for a short time.
When Marth reclaims Archanea Palace in Chapter 12, Nyna gives him Parthia. The Whitewing Est would later sneak into Grust and reclaim the sword Mercurius, taking it with her into Marth's army. Camus of Grust holds the Gradivus, and drops it after he is defeated by Marth's army.
During the War of Heroes, the Three Regalia begin the war firmly in Archanea's grasp. Parthia is in the hands of Jeorge, who takes it with him when he joins Marth's army, Mercurius is wielded by Astram, who uses it against Marth's army until convinced otherwise by Jeorge, and Hardin himself wields the Gradivus.
- The Gradivus appears in Fire Emblem Gaiden, although whether or not it is the same lance is unknown.
- The axe Hauteclere is said to be on par with the Regalia, but its origins are unknown.
- In the Archanea Series, there are no available classes that are able to use all three regalia, despite Adrah having used all three himself.