We-ell, the problem with duelling is professional duellists.
How to commit legal murder in a society that allows duelling:
1) Provoke a duel with the victim.
2) Hire an assassin as your stand-in in the duel. A dandy versus a professional killer? It's little short of murder.
Another trick mentioned in
Scandinavia was that duellists would stake claim to other people's stuff, and offer to fight duels to settle the ownership.
These and other reasons are why we settle things through laws and juries these days, rather than hacking each other to bits.
I personally would like to see more trials by ordeal
Tongue-in-cheek,
Brian P.