Giant Hand Baru was indeed a Lord of Mourning, without a doubt, the most powerful Undead beneath the Monarch in this Plane. However, its reputation was not prominent; outsiders only knew of Gust, Nosarlo, Arambrough... because Giant Hand Baru had been locked away.
"Locked away? Is there something that can actually confine a Lord of Mourning?" Negriss exclaimed in surprise.
"Why couldn't it be confined? Under the constraint of a Soul Oath, even if Your Majesty drew a circle and ordered it to stand on one foot, it would obediently do so," Kent said.
"If there's a Soul Contact, then why do you say it harbors rebellious spirit? Is it capable of betraying Your Majesty?" Negriss asked, puzzled.
"It's not bound by a Soul Oath to His Majesty, but a loyalty oath. Most of our spirits don't have a Soul Oath with His Majesty. His Majesty says such constraints are bothersome; if he wants to do something one day, he'll have to release them first."