paarthurnaxVopruziig
This looks like a good word for the above. Maybe it could be shorter.
There's a problem with this word. It means "ungood/evil", not really "vice". Vokul already means "evil" and it's Canon.
(what does the suffix 'iig' mean? I can't find it).
I don't think "Qeln" is bad. The "eln" sound already exists with some words.
"Sin" and "Vice" should probably be the same word in this lexicon though, even if they are technically different things, a "vice" is something that you do that isn't kosher that gives you pleasure, and, well, a "sin" could be that, if the vice was "sinful".
If "Qeln" is used, "Zoqeln" could be "sinful, full of vice(s)". "Zoqelnaar" sinfulness. "Qelniik" sinner. Doesn't seem too bad.
If we go with the Canon word "Vokul", evil, "Zovokul" would mean "sinful, full of evil", "Vervokul" would be "to sin/commit evil", but to be/make evil and to sin are NOT the same thing, not REALLY....... Unless we wanted to make the word "sin" equatable to "evil" in this lexicon. Not impossible.