For your next shield, you should get grey owlite shield, since FSC is gonna be a fire themed, Or if you have a short budget on your shield (only have 2) or having a hard time dealing with trolljans then you should get the volcanic plate shield.

Here is how you beat a greaver:

-Use your strike needle's normal attack to stagger the greaver as it trying to approach you, you should have a short interval before the Greaver begin the fast attack move.
-Once you stagger the greaver (you can tell when it stops moving), close in on the Greaver with your DA and use shield canceling technique and hit it repeatedly with DA's first hit (never use the combo, just the first hit them then shield cancel)
-if there are multiple greavers, you will have have to shoot the strike needle accordingly. Think of it as your shotgun, and fire its normal attack--> move away from the greavers--->shoot--->move away/shield--->shoot--->move away/shield

And you should also consider crafting some new armors as well as weapons, here are some gears you should look into:
Angelic raiment (valkyrie): gives you damage bonus against Greavers, but be warned,it is very weak to fire.
Flourish (sword): it is probably the best sword for greavers.
Angelic helm (fallen): this one gives you damage penalty against greavers, but, combining this helmet with you cog cub coat, you will have a healthy defense for both elemental and shadow attack, which is the main component of the FSC, and on the top of that, you get maximum fire resistance and fire is the maintheme of FSC, so you should check this one out as well.

try this thread
http://forums.spiralknights.com/en/node/81809

if you ignore the complaints there are some good tips in there

When I first came up with a tactic it was about dropping Hazy Haze Bombs and kite the greavers. I died too much because I couldn't outrun them when I charged the bombs. Kind of useful for quicker persons. Not for me.

So instead I started gunkiting them. I shot them while they were not attacking me and ran for my life when they were. Once again I died because of my unquickness and the clouds didn't make it any better.

Then I gave up and rushed into the mass of megabats and shot everything that moved. It worked. Much better. Turned out that you can interrupt the filthy little flyers easily by hitting them. One hit from an Argent Peacemaker is enough. Still died, so I think I'll have to work out a better tactic, but I only died once.

Right now my new tactics involves:
Get a sword
Get good armor
Get a piercing sword
Do not die
And GET A SMEGGIN SWORD

1. Acquire ANY toothpick weapon (yes, even 2* works, even in T3 elite arenas with 12 Greavers). Flourish is easiest to get and has an ultra single target attack, but Snarble Barb has the looks and crowd control. And no one can argue with looks. Not even Bill Cosby.
2. When them Greavers attack, hide in the corner. Use Shield Cancelling and spam the first wide swing at an angle that covers your entire exposed area. No, not that exposed area. Don't you know that's illegal?
3. Laugh maniacally as your dead friends watch in awe as you beat up a dozen elite T3 Greavers with a 2* toothpick. (Author's note: I am not responsible for any hospital bills for wounded wrists from clicking so long at the T3 elite Greavers with a 2* toothpick)
4. If some other annoying critters appear with the Greavers (Mecha Knights, Devilities, turrets, Nicholas Cage), dash to another corner while unleashing a charge attack at said annoying critter. Preferably Brandish line, which will knock back (or disrupt) the said annoying critter long enough for your dash to recharge. Repeat until said annoying critter is dead. Laugh maniacally as your dead friends watch in awe as you not only beat up a dozen elite T3 Greavers but also said annoying critter(s).

OPTIONAL, IF YOU DO NOT WANT MEDICAL INJURIES FOR HURT WRISTS WITH A 2* TOOTHPICK SPAMMING AGAINST A T3 ELITE GREAVER:

Sprites!

Maskeraith: The cloak can be quite helpful, be it you want to escape from Greaver detection to heal or if you want to look epic (which, admittedly, is a perfectly normal reason to waste the cloak anyways). Otherwise, the miasma can be effective at disruption of annoying Greavers.

Seraphynx: The IMFIRINGMAHLAZER blast can be a lifesaver if you lagged (or are plain noobish), as it has excellent disruption with little damage (so you can still take most of the credit for beating up T3 elite Greavers with a 2* toothpick). The Guardian Aura thingymacguffingmcbobbermajiggy should be able to protect you from a blast or two from the Greavers, assuming you can use it well. Heart Attack? Ehh. If you follow my strategy you won't need no Heart Attack!

(Gets a heart attack)

Vogdarnit.

Drakon: Fire Barrier is great for several reasons: it reduces damage taken, it deals minimal damage for the credit claim, and you GET TO WATCH AND LAUGH AS YOUR HATED FOES BURN TO ASHES AND SHREDS! MUAHAHAHAHAHA! *Ahem* Anyways. Fireblast is good for crowd control and for SETTING THE HATED FOES ON FIRE AND BURNING INTO ASHES! MUAHAHAHAHAHA! *Ahem* ANYWAYS. Firestorm? Eh. Not really that good, but you go get to SET YOUR HATED FOES ON FIRE AND BURN THEM INTO ASHES! MUAHAHAH-

/e slaps xyrself. Ouch.

Equipment, you ask? Good gear, you ask? All you need is the 2* toothpick, a moderate connection, and preferably a Drakon so you can WATCH AS YOUR HATED FOES BURN TO ASH! MUAHAHA-

/e slaps xyrself. Hard. With a chair. Ouch.

So, anyways. I guess that's all for Sandy's guide to beating up Greavers. Don't follow me (as that would be creepy) and don't like either (since that's gross and even creepier). Gah, who invented these online terms anyways?

I also had my trouble with greavers initially, but i discovered two ways that worked for me perfectly.

1. (I used this before the Greaver reclassification. Need reconfirmation that it is still working):

When entering a Fiend themed depth I used to run a round with a charged 5* Calibur. As soon as a Spawn had Greavers (usually 4) I did let them all come and smashed them away with on swing, retreated to charge another load and kept investigating.

The tactic is: Kill them before they can even attack you; if you show any fear, they will eat you.

2. My actual tactic vs Greavers, since I wasn't that successful with a piercing sword and prefere a gun anyway.

Storm Drivers were the most relieable weapons against them if I only use the first shot and shield until I can use another first shot. A shot will not only interrupt the current attack and deals damage, it will also give Greavers the shocking condition, that will interrupt them later while you keep fighting with them.

If one comes too close, just use a short shield bump and it is at distance again. This doesnt cost Shield energy and is a safe way to keep those Greavers at distance.

You guys are making this overly complicated, just get into a corner and swipe them with your sword

EASY. Every time they charge the attack. Swipe at them one time and that cancels it. Easy. Barbarous Thorn Blade is overkill for them.