Hey now, My name is not foreign! I was born here, And have lived here all my life! My name "Red Slayer" was passed on to me from my grandfather who fought in an ancient war, His armor was red, And they called him "The Red slayer" Because he seemed invincible and killed many enemies, with what seemed to be no effort at all. So when I was born, My name was given to me, So that maybe I could be passed down some of his strength as well. And ofcourse, to carry on his memory.
As for the other people with Slayer in there name, They probably got it from his legend
(P.S. Also, I'v been here for 2 years now, And I know you're talking about RoS, But still
)