And I quote:
"Greavers have been newly classified as elite monsters, much like mecha knights and gremlin thwackers. Designed to pose a greater challenge, the already challenging greavers have received a health boost and will now be less prone to showing up in large swarms."
So why do they still appear in arenas by the DOZEN? Not only that, but their shock attack is half the time invisible, lingers way longer than it should, and they ALL attack you at once from anywhere on the screen, so even if you do manage to shield them, they break it on 2 seconds and you can't even MOVE! Even swords don't help because they surround you from all sides and you have nowhere to go.
Give you a hint, unless things have changed, inflicting damage to a greaver cancels its attack, now you can use your other observation that they all attack at the same time to know your enemy. Attack them right after they telegraph and dont spam a full combo or clip because you will most likely be reloading or doing whatever it is that swordsmen do after their swings when they attack again.
Edit- Also dont just sit there and soak damage with your shield, bump them and find a better spot to stand.
~Luke