Sephuz's Secret is kind of a reference to a scene in Kung Fu Hustle, where The Beast (the bad ass bad guy) shoots a gun at his own head point-blank and catches the bullet with his fingers, then says something like "In the world of kung fu, speed determines the winner." I always thought that was really bad ass, and Sephuz's Secret is a speed-themed item (movement speed, haste) so there it is.
I've always loved flavor text (probably stemming from my MTG days) and love adding references to names/flavor text of things. I could probably do an entire writeup just on references in the names and flavor text of legendary items. Many of them players have figured out (e.g. Tak'theritrix's Shoulderpads) and it definitely makes me really happy to see when people get it.