Actually, SkekEkt is lust and SkekZok is pride. During the film's time, we only see so little of SkekSo, so unless there are production notes on him, it's hard to pinpoint his sin. But the rest are spot on.
I ate a pear. I ate three pears. - Lizzie Borden

SkekOK is Sloth, SkekAyuk is Gluttony, SkekEkt is Pride, SkekUng is Wrath, SkekShod is Greed, SkekSil is Envy, and SkekSo is Lust. SkekOk is fairly senile and can often be found sleeping. SkekAyuk is not only morbidly obese, but also displays a complete lack of table manners during the feast scene, even more so than the other Skeksis. SkekEkt is notably effeminate, wears especially extravagant clothing, and eats more delicately. SkekUng relishes attacking SkekSil and greatly enjoys watching him being banished. SkekShod is usually silent and is preoccupied with chewing on gold. SkekSil is next in line for the Skeksis throne and craves it above all else. Contrary to popular belief, lust can refer to any form of desire, not necessarily sexual. SkekSo's insistence that he is "still Emperor" certainly qualifies as extreme desire.

I think all Skeksis share the same sins,more or lessI think the High Priest represents Pride and the Ornamentalist( I love him )vanity,its a matter of nuance

Even though I know Skek-Ekt was male now, I still think of him as female because that's what I thought when I was little! A female Skeksis is pretty cool.

SkekEkt: "Oh, how CRUDE!"
Jar-Jar Binks: "How WUDE!"
"Wings?I don't have wings!?"
"Of course not. You're a boy."

Yes,but Skeksis arent the Smurfs to have only oneBetter there arent any female,that doesnt allow them to procreate,ha,ha!
Wed better leave this,we were speaking about sins,and his is,of course,vanity.

They are revolting,those people shoul go to jail!and STOP SAYING THAT,please!

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That was no female,HE was Skek-ekt the Ornamentalist (hes my favourite),and I dont see what lust has to do with good table mannersbut hes supposed to be a sensualist character (in the films production notes).
THERE ARE NO FEMALE SKEKSIS!

There was a female in that group. Remember when they were eating and she was eating daintily from a few forks. Perhaps, lust?

I think lust is changed into the sensuality of their lives,and they are supposed to be very slovenful,specially the Gourmand,hes so fat!

The Treasurer could quite possibly be greed. But who has lust, then?
-"In 300 years, when Evil returns so shall WE!"