shark as you said down here so thats a good think so my vote is +1

+1
Helps player without anyone else interfering with their fight

+1 for it but annother cmd that cancels it off so that people cant abuse it then it would be awsome!

+ 1
Maybe make the player you challenge to the duel accept/decline the duel* as option to stop cmnd abuse  

if someone duel request us instead of a pop-out box we get a notification in main chat.So we not got freezed due to pop-up while fighting.We just have to do /acceptduel to accept the duel request above^ ...

And we can not tele to zones while doing duels coz anyone can tele and abuse those weapons ...
And if someone did /duel Player ID weapon id's like(36-41) both will get banned <<<   

It can be easily abused so -1.

After the duel Done...
Each player will be spawn in each base
So they won't abuse the duel weapon  

Okay my part
+1 from me

I think the server is going to dm serv not tdm
Can add only leave duel with /kill, disable all cmds
And when some1 won, winner get Spawn too