I don't have any strong feelings towards Zack as a character, but I wouldn't be bothered by an awesome sword fight.

Zack: I'm a First Class SOLDIER same as you, and I am going to beat you! -charges and swings blade and stuff-
Sephiroth: -yawns, parries blade with ease, thinks about Mother, Shinra, other stuff, lazily swings sword and matches Zack blow for blow
Zack: I feel like you're not even trying.
Sephiroth: Don't have to. -smacks Zack so hard he flies out into the other room- You're just a puppet.
Zack: KO!

On second thought, I'm good with a squash match.