I got an idea.
Godsword Pure/Zerker - This setup uses power to overwhelm their opponent. Their weapons are uber strong, but a slow. Their damage and accuracy make up for their speed, as well as their bonuses and special attacks.
Bandos - Lowers Defence, Strength, Attack, ect. by damage delt (In order, lowers stats by 15 at least). This is bad for Zerkers, but disasterous for Melee Pures. Since they usually have 1 Defence, this get knocked off first, then their Strength is ruined. While they could use a Restore Potion, it weakens them and makes them waste time restoring and reboosting their Strength (Not to mention you can use Restores in a duel anyhow)
Armadryl - Their Special boosts the damage dealt by 50% AND can be used consecutively! With this weapon, Pures will be torn the shreads and will knock Zerkers down!
Note: The other Godswords are just as strong (Stat wise), but their specials are more better off for PvE (Player Versus Enemy) or in other PvP Situations.
This could be a decent setup for dueling, I'll try to add more ideas I have later.