Question about tenchi series spin off?

in Isekai no seikishi monogatari tenchi's half brother gets transported to a parallel world. now if he is Tenchi's half brother then he would be the son of Tenchi's dad and Rea Tenchi's step mom making him human but in one of the episodes close to the end he materializes a sword like tenchi and he has marks on his forehead like the Juraian family. so how does that work? if he is human he should not be able to materialize stuff. even if he was a decendent of one of those cores for the fighting robots he shouldn't have the abilitys and markings of a Juraian. so what is your theory on how he was able to do that.