Master-at-arms of King Randor's army, chief weapons inventor of Eternia, and adoptive father to Teela. One of the very few Eternians who know that Prince Adam is He-Man and one of He-Man's most trusted allies.
Man-At-Arms (Duncan) is the master strategist and weapons inventor of Eternia, serving as commanding officer of the Royal Guard and personal advisor to King Randor. He is also the adoptive father of Teela, having taken her in as an infant at the request of the Sorceress.
He is one of a small handful of characters who know that Prince Adam is He-Man, and serves as a mentor and tactical advisor to both identities. Most of the iconic Eternian vehicles, including the Battle Ram, Wind Raider, and Attak Trak, are presented as his inventions or designs across the original toyline and the Filmation continuity.
In the 2002 MYP series the character was redesigned with a sleeker visual silhouette and given a backstory tying him more closely to the Royal Guard tradition. The Revelation continuation, with Liam Cunningham voicing the role, expanded the character significantly, framing Man-At-Arms as a grieving father whose moral authority anchors the rest of the cast during He-Man’s absence.
Catalogue source: heman.fandom.com (CC BY-SA 3.0).