I have me some vog and skolver, I'd say go vog. Even in non elemental lvls the speed increase helps and with the slow swords you can get the 2nd hit in before the enemies strike back. With the skolver you can only get 1 hit in, or you usually get hit if you go for the 2nd. You can do T2 bosses with vog, and also it rules for FSC. Skolver is useless in FSC, one hit and and you're dead, or if you catch on fire you lose most of your life, so if you want to do the T3 boss you'll need another set of fire/elemental armour. If you do the thorn shield too part of the bonus is wasted with the skolver. With Vog and a thorn sheild you have attack speed very high and damage medium, then you can also get a sword damage trinket too.

Vanaduke is hard, if you gear up for him you can pretty much do anything.

For weapons, for the Duke the best are
Divine Avenger
Polaris
Shivermist

Some people also bring
-Something with normal damage for his mask phase - Leviathan, Cold Iron Carver, Dread Venom Stryker, etc
-A peircing gun to get through his fire ball shield - Argent peacemaker, blitz needle - although a polaris does almost as much damage to him and you don't need to aim and its a lot more useful everywhere else, the snarble barb charge also works
-I see a fair number of people use a Combuster or Glacius instead of the Divine Avenger

So you basically need weapons for 5 situations
-Sword for Fire Zombies (Divine Avenger, Glacius, Leviathan etc)
-Gun for Fire Zombies (Polaris)
-Normal Damage sword for the duke (Leviathan, venom striker, etc)(or Avenger or others only doing their half normal damage)
-Peircing gun for the duke (Argent or needle or Polaris, or snarble sword)
-Crowd Control (Shivermist or Polaris)

For general T3 levels that aren't the boss I like
Gran Faust/Divine avenger combo with a polaris for backup, with this you can kill pretty much anything
You can replace Faust with Archeron and Avenger with Combuster or Glacius if you like the faster swords
Snarble barb is great too if you're up against fiends or wolves

Other stuff is good in certain situations but anything mentioned above is good for general purpose carnage

@thriller : everything seems correct except a little error : skolver set = damage very high and thorn shield = damage medium, so both are doing damage : maximum and nothing is wasted. Then you have to take ASI trinkets.

My opinion : DA is great, go for it, there is a reason this is the most popular sword. For shadow, I don't like not having a reliable charge attack, so I went for Acheron line, it's good enough (but, well, not my favorite weapon ...). And for piercing, Snarble barb is awesome, my favorite sword : fast, stylish, and huge knockback.

If there is an all purpose gun to have, it's really the Polaris. It only do reduced damage to Beast and Gremlin, and you don't want to use this gun for those anyway, swords are generally easier to deal with those.

And obviously, Leviathan is THE sword every swordsman (heck, even every gunslinger and bomber) should have. Well rounded, and awesome charge attack (except for your teamates, but it's up to you to not throw anything on them).