Sorry, wasn't able to find the RELz thread of Duel here in the forums.

Yesterday I was reading about an update to version 6, today I find no trace of Duel on the Nexus.

Has the mod been removed ... abandoned?

The author actually removed it because he didn't like a review he received. I won't comment or add opinion in case I start a fire, but those are the facts.

http://www.gamesas.com/topic/1459544-shouldnt-we-have-greater-emphasis-on-content-mods/page-7#entry22665488

I just read the review, and all I want to say is that I think the reviewer needs to learn the difference between criticism (complaining for the sake of complaining) and constructive criticism (encouraging the author to improve things). I use DUEL myself and I think it's the best combat mod out there. Combat is more difficult, but not too difficult, and it has a great staggering effect that makes the player view go down to the ground, so when you get hit, you sure feel like you're getting hit.

It's a pity that the mod was taken down.