What exactly was different when her siblings gave Sisu the stone than when Raya gave Namaari the stone that made it so powerful that unfroze the dragons and not just humans? Furthermore, Chief Benja's sword, which Raya wields after her father is turned to stone, is an Indonesian kris sometimes called keris , which has a wavy blade and as well as a weapon.
It's implied from her initially refusing Boun's meal that she's used to going hungry, and makes handfuls of jackfruit jerky to stay alive.
It's one of the only things that can protect you from the Druun! In essence, Raja yoga is the yoga of mind and body control, with a focus on meditation and energetics.