This is from The Adventures of Huckleberry Finn by Mark Twain. Here is the link to the source: https://www.sparknotes.com/nofear/lit/huckfinn/chapter-5/
AIN’T you a sweet-scented dandy, though? A bed; and bedclothes; and a look’n’-glass; and a piece of carpet on the floor—and your own father got to sleep with the hogs in the tanyard. I never see such a son. I bet I’ll take some o’ these frills out o’ you before I’m done with you. Why, there ain’t no end to your airs—they say you’re rich.
This is the modernized version:
“Ain’t you a sweet smelling little sissy. You’ve got a bed. And sheets. And a mirror and a rug on the floor. You’ve got all that while your father sleeps with the pigs in the tanyard. I never saw such a son. I bet I can beat some of this fanciness out of you before I’m done. And that’s not all. They say you’re rich. How’d that happen?”
My question is, why is "dandy" replaced to "sissy"? "Dandy" means "concerned about styles and look", but "sissy" means "a coward".