CIV is a normal sword with low base-line damage. So that's pretty bad. It has an undead bonus, but this is not very valuable if you plan to have a lot of damage bonus from other sources. For example, a Levi with damage+6 out-damages CIV with damage+6 even against undead. On the plus side, CIV's charge does less knockback than Leviathan's. So it's more party-friendly, and it's easier to land multiple hits on enemies, for high charge damage. Still, there is little doubt that the elemental swords are generally better for killing undead (and certainly constructs, and by the way also slimes and fiends).

So why does CIV exist? For the same reason that WHB with its beast bonus exists. These swords have not been changed since Spiral Knights launched. Back then, there was no Barbarous Thorn Shield, offensive trinkets, or Snarbolax Armor. The only way to get sword damage bonuses was Skolver and UVs. So monster-specific damage bonuses were fairly valuable. Nowadays, any serious sworder has lots of blanket sword damage bonus, so monster-specific bonuses are not very valuable.

Oh, no, the CIV is definitely not useless. See, the thing here is, it is normal damage, while the brandishes are elemental. The undead are weak to elemental damage. CIV, however, also has a bonus against the undead, making it more useful for them. The thing about CIV, is that it is normal damage. This makes it better as an all rounder, whereas the brandishes may be really good at undead and constructs, but not so good on gremlins and beasts. Therefore, CIV is certainly a viable choice. It just kind of depends on whether youd rather have a specialized damage weapon, or a weapon that does decent damage to everything.

And don't stray away from a weapon you might want just because its damage may be a bit less than its competitor. Each item has its own niche and use. Mix and match and try to figure out what works the best for you.

~Magnicth

@Fradow: When I said it was more useful for the undead, I meant for that sword exclusively, that among the damage types, it is used more against the undead. I was not comparing it to the elemental sword lines. And it is quite a viable choice, seeing as it would provide a sword that is decent against all enemies, and would save Cao the time and money of making multiple different weapons of different damage types. And just because it may not deal as much damage as the elemental lines doesn't mean that it isn't a viable choice.

~Magnicth

I consider it as the "poor man's sword". While it deals more to undead, it deals less normal damage than a Leviathan would do. While it is good to do an FSC run (without Vana), Leviathan swallows the Vanquisher up if someone gets lucky enough to roll a "Very High" UV (Specifically ASI, CTR, DB vs. Undead). Thus, wealthier players should go for Leviathan. While it isn't a great solo weapon in the long run, your party members won't kick you for your Levi charges. That being said, it also depends on your playstyle.

Against an elemental sword, Cold Iron weapons are EASILY outdone in terms of damage. A monster's weakness to a type equals more damage compared to a weapon strong against a monster. On top of that, the elemental weapon can STILL get a DB vs. Undead UV, which would then crazily outclass the Cold Iron weapons.

So why get a Cold Iron Vanquisher in the first place? A CIV user is guaranteed additional damage against undead, making it a useful grinding weapon early on. On the other hand, a Levi / Elemental weapon user would have to roll again and again before finding the desired UVs.

The swing alone of a brandish charge roughly equals to 2 hits froma levi charge. Forget about the explosions.
You can hardly land 2-3 hits on a Levi charge unless the enemy is cornered/frozen/turret.

The real advanatge is it's 360 range. But when you're fighting you instinctively try to avoid getting surrounded right?

It look cooler than any elemental sword :D... it have chains! CHAINS!