(Two men enter. One man leaves.)
Just no. It's a line that should be in one of those awful American action movies full of exploitations, not in Buffy.
In point of fact, that phrase was first used to describe the gladiatorial games in ancient Rome, and the movie that you're referring to, "Mad Max," was Australian, not American.
This is definitely one of my favorite episodes of Season 7, and probably the entire series. I've always been a sucker for the big climactic one on one showdown between the hero and the chief bad guy (okay, the First Evil was the chief bad guy, I know, but Buffy couldn't very well slug it out with an incorporeal being) and the final scene with Buffy and Spike, to me, affirms without so much as a spoken syllable the depth of trust and love shared by these two characters. Argue whatever you want to about whether or not anything romantic exists between these two, this one scene affirms a depth of love, faith, and loyalty that equals or goes beyond anything else in the entire Buffyverse. In any good series, there are scenes that make you want to cheer, to cry, or both at the same time, scenes that define the characters, their relationships, and the very essence of the show, and this, for me, is one of those scenes.