DID HE EAT HIS BROTHER'S ASHES OR I GOT IT ALL WRONG ????

He ate the ashes of the things Sam-myeong left behind, which were burned, as you could see.
The brother's body was never found.

Oh thanks, that makes more sense in a way...

If I remember correctly he also did eat several poisons so that he would become immune, so it’s more likely that especially with the vomiting.