It refers to legendary weapons from Kobolds And Catacombs expansion, there's one for each class. Aside from Skull of the Man'ari, it provides quite a value. Also - burgle rouge syneries (preety nuts with Tess), unless you get Kingsbane of course :)
"Teron'gor decided that if death and resurrection didn't count as a legal name change, nothing would."
Dreadsteed, of course, is the game's first undying minion. Teron'gor's own Death Knights forces it to be nerfed to prevent Defile from going infinite, but provided the perfect effect for this card. Essentially you have your very own Silver Hand Recruit from turn 1, but one that's not only susceptible but constantly threatening your healthpool. Short of silencing it however, it's inifinite value onboard... provided it doesn't die fifteen times.
Oh, and Gorefiend? Gorefiend just chump-blocks. Summoning hell steeds is hardwork, man.