I don't really now how overpowered Eggwars works in 1.9 or above Java, but in 1.8, I think that everything is very balanced already.
Due to the nature of the game, which is basically spamming your left mouse button, in OP 1.8 Java Eggwars, the best way to eliminate someone would be to either break their armor or knock them off an edge. Especially end-game, where players have full diamond armor with crazy amounts of enchanted gaps. From what I have observed, fights in 1.8 tend to be a lot shorter and the only way to make it longer was to add overpowered gear and weapons into one of the gamemodes.
From my experience(which is not much), on the 1.9 or above Java network, fights in Eggwars are slow-paced and more strategic. So I think that this would be a good idea, maybe lowering it down to Protection 4 or 3. I don't know if the server has a custom plugin that changes the Protection armor values, but the vanilla version of Protection is basically the armor value times 4.
Prot 1 ~ (1 x 4 = 4) 4% damage reduction
Prot 2 ~ (2 x 4 = 8) 8% damage reduction
and so on, though theoretically if you were to have Prot 25, you would have 100% damage reduction, but this is capped at 80%, there are a lot more other variables to this but this is one of the main factors.
So if Prot 5(20% damage reduction) were the current value that the armor was at right now, it could be changed to Prot 4(16% damage reduction) or Prot 3(12% damage reduction).
So in my opinion I think the armor values should be changed on the 1.9+ Java network and not on the 1.8 Java network.
Sorry for the long post, I kinda got carried away.