Hi,
I'm playing a greatsword paladin in our RotRL campaign and we just finished the catacombs of wrath
Usually if I hit something it dies and our other members feel quite weak when it comes to damage.
Another thing is that we played the beginner box as well , but we remade our characters so that we didn't keep any loot from it, and I am not sad about it. We don't have a lot of cash or any real Magic items yet. So we try to get equipment with diplomacy and roleplay (thanks father Zantus for our holy water). Maybe the longsword (which my paladin had as well in the beginner adventure) makes things a bit unbalanced ESPECIALLY if they are going to sell it, if I remember the value it was quite high , so that you could purchase many useful stuff.
As others already suggested I would target the barbarian with some arrows and sneaky stuff or difficult terrain. My paladin had the same problem as well.