Yes, they definitely should not be infused with the dark will and should be less than the Seven Deadly Lords. And I like the good Doctor's idea. I can sort of see a Darth Vader thing going on. Lust says, "Sadism... you have failed me for the last time. Next candidate!"

And maybe not call them Lords of X... maybe a different title, like "Duke of Sadism," or something similar but more cool.

How about 'Viscount'?

Duke flows better in a title, at least to my ear. Also, has traditionally been one of the titles of various major devils.

Duke it is then

Duke was just one idea. I don't love it. Throw out some more ideas for lesser Lordling titles.

Ack! And me without my AD&D Dungeon Master's Guide!

Seriously, one of the appendices has pretty much EVERY title you could ever want or need. Lemme see what I can find.

Historically correct titles

Alternate titles developed by the SCA

If the Dukes of Sin are essentially lesser nobility, why not let each Duke pick their own title? That is, use the title that fits sounds best with their sin?

Ferinstance, "Marquise of Sadism" definitely has more of a dominatrix ring (sting?) to it than "Duke of Sadism".

The way Farland is setup, each region might have its own cultural titles for nobility. What the English called a "Knight" was a "Ridder" to the Danes and a "Chevalier" to the French. Using culturally-specific titles (or not) could be a perverse way of keeping cultural pride ... or an attempt to subvert it.

Either way, the setting wins.

When I posted this, I didn't actually mean an actual D&D artifact. I was thinking just a powerful magical item. However, I just remembered the Concordance feature of artifacts. Again, this plays well with, "You have failed me for the last time!" Each Duke of Sin must continually strive to maintain Concordance with their Mark of Office AND remain in the good graces of their respective Lord. The two goals may not always be compatible...

Just another idea to tack to the board.