Faydwer faction
 

Is there any reason a SK would want to keep this faction? Like epic reasons or anything I might be missing??

Felwithe guards, in particular...

No. All the evil classes/races are designed to have evil faction for all their quests.

For instance, even Ogre/Troll/Iksar Shaman can complete their epic quest ... despite the fact that a part of it is in North Freeport. You just have to use a spell on your list (Invisibility) and the Freeport sewer system, because the original devs have the NPCs located in places that are safe to Evil folks.

Good factions are only useful if you want to do random Good quests, or sell/bank in Good towns. Otherwise ... have fun harvesting elves for plat ;)

I quad in oggok just to emasculate the stoopid ogres with my halfling. Then deny them ports and sow!