“Friendly duels” create a false sense of security.
The first thing you should do when coming up with suggestions for EVE is to think of how EVE players would exploit such a feature.
And someone with malicious intentions could easily do so by initiating such a “friendly duel” with a ship they would like to destroy, fight legally to hull and then use a second person to gank the target with significantly less cost when the target is already in hull and vulnerable.
So much for a “friendly” duel!
And now we’re back at exactly the current situation where people won’t duel others in ships they cannot afford to lose, and won’t duel people they don’t trust.
The only notable change is that you created an opportunity for a new scam that is going to get spammed anywhere in local “Friendly duels at sun!” where people just try to find gullible players to kill by pretending to have a friendly duel and then kill them anyway for their loot.
It’s just as risky as the current duels, except the game now lies to the players by pretending it’s ‘safe’.
A downgrade if you ask me.
‘Friendly’ duels are only safe from that one other player, but EVE is an MMO with more players than just you and your friend. All those other players (or characters) are not restricted by whatever rules you two set up with your ‘friendly’ duel and can interfere after or even during your duel.
A mechanical solution to prevent such a strategy could be to provide a magical shield to stop people in duels from being vulnerable to ganks, or magical healing to make duelists magically recover their health if they get attacked during or after the duel like some other MMOs might do. But EVE is not other MMOs, EVE is not magical and such a feature would be silly and out of place. In addition, people would again exploit such features to either protect themselves from PvP with this magical shield, or to exploit it by getting free repairs through dueling in case no logistics ship is nearby… and so we get into a situation where the mechanics get increasingly more complex, convoluted and exploitable.
No, the best solution often is the simplest one:
Dueling works fine.
Dueling simply is a mutual agreement to lift the HS engagement restrictions so that a player is allowed to legally fight another player in HS, just like any player can already freely fight a friend anywhere else in space outside HS where these restrictions do not exist.
There’s no need to add magical protection. If your friend cannot hold themselves in and cannot stop shooting when you’re in hull you don’t use an expensive ship or you don’t duel that friend.