Aww man I see now so this was all a test to see how he would react to the fact he had to kill his friends for the sake of the world taking on the responsibility of the new ruler, cause their demon sect would he go through with it. Which I hope he don't cause sometimes you have to look at the other side point of view, just like the thought people can change and so I think at the end, he didn't kill them by choosing that path he passed the trial making the ancestor sword accept him as the new ruler.

The best sword chose him and all the other swords went away because the strongest sword said outta the way I'll be his sword, because as the strongest sword you would throw everything away to protect your loved ones even if it meant dying with them, which is why the strongest sword picked him because his willpower is strong, not like those other people that are greedy y'know.

Agreed, except I'm thinking the test isn't so much about if he'd protect his friends as much as it is about if he'd be capable of not being swayed by others (especially when they're people he's close with and respects/looks up to) and still be able to stick to his own morals of protecting/helping innocents or those in need, regardless of their clan/sect. Almost like the sword's objective is to find an owner who could unite everybody and finally put an end to all the discrimination fueled fighting/killing.

Makes you wonder about what kind of outcome he might've chosen had he never had the relationship he did with that demon girl though. But that being said, I'm sure that was most likely all taken into account from the jump, which was probably a big reason why that old guy had them travel together in the first place...

Yea that would make a lot more since, to the reason why his master and the people he respect would pressure him into going against his very moral. Where so many have probably failed the test thinking that's right path to take, but by doing so would get trapped by the sword. If like The ancestor sword was judging him while all the other swords were compelled to look like kill him.