Sakido's wings were badly injured in a skirmish with some Warrior Angels which also claimed the lives of her parents, she was unable to fly on her own ever since. Darius initially tried to comfort her by carrying her whilst flying himself but Sakido desired to fly on her own. At this point, Darius realised that it might be possible for Sakido to wear his Sun Emblem as it had a Holy Protection Spell cast on it. As an artisan Angel, he was able to remove the spell so that Sakido could safely wear it without it harming her. Sakido became the first of Darius' adopted children to receive one of Darius' Angel Emblems, acting as the test case which would eventually allow Darius to save Buwaro.
When Sakido put on the pendant, she immediately grew new, strong wings that enabled her to fly extremely well. Sakido later went on to become one of the strongest Wind Warriors in Hell which the pendant may have helped with. She also started wearing the Emblem under her clothes, presumably to hide it from the other Demons.
When Sakido died, the Emblem was passed to her younger brother, Buwaro by Rhea as part of Sakido's verbal will before she left to fight. Buwaro initially just carried it in his hand but eventually decided to put it on which had the same effect on him as it did on Sakido. Buwaro is a Fire Demon, not a Wind Demon so his wings are too small to fly. It isn't clear if Buwaro derives any other benefits from wearing, Sun Emblems are supposed to "calm the hearts of Angels" as well as granting wings.