Buzz
Sasuke handed over his precious headband to Boruto as a token of trust and recognition towards his student.
The Leaf Village headband became a valuable possession for Sasuke after reconciling with Naruto following the battle in the Valley of the End. Years later, Sasuke became Boruto Uzumaki's sensei - Naruto's son.
Talking about headbands in Naruto, it's essentially a metal plate engraved with the symbol of the shinobi village, accompanied by a cloth with various colors. This headband can be worn anywhere, but most people usually wear it over their forehead as a self-protective item.
After discovering Sasuke as his father's rival, Boruto requested to become his student. As a sensei, Sasuke taught his disciple many things and witnessed his growth over time. Seeing his disciple as a brave and mature shinobi, Sasuke got used to giving his headband to Boruto at important moments.
In the Boruto manga, Sasuke's headband isn't something Boruto Uzumaki regularly uses as one of his main accessories. He often uses his own headband, occasionally resorting to Sasuke's. Sasuke himself doesn't regularly wear the headband but always carries it with him.
In chapter 49 of Boruto manga: Naruto Next Generation, before Sasuke leaves to assist Naruto in facing Isshiki, he notices Boruto's unease. His student fears Momoshiki will take over his body. Sasuke promises to stop his disciple if that happens, even if it means sacrificing Boruto's life. Since Naruto isn't brave enough to do so, Sasuke takes it upon himself to reassure Boruto.
At that moment, Boruto asked to borrow Sasuke's headband, just as he did in the battle with Momoshiki. Of course, Sasuke willingly hands over the headband and asks Boruto to return it when they come back. Sasuke does this because he fully trusts his disciple and believes he's strong enough to overcome challenges.
