Hattori Hanzo is, of course, the greatest swordsmith in the world, according to the movie Kill Bill. Losing your Hattori Hanzo blades would be the equivalent of, say, having the entire tax bases of the East and West Coasts suddenly vanish from America. Yeah, it’s like that.
“Yoicks” is actually a call used by English fox-hunters to urge on their hounds. In this context, though, I’m using it a la Daffy Duck as in his infamous “Yoicks, and Away!” from the 1958 cartoon Robin Hood Daffy. In the S-Team strip, the “and Away” would come when Slick runs for his life from Silence, which you’d do too if she was mad at you.