After collecting a few more Eridian weapons, I managed to take the thing down pretty darn quickly. A pair of Eridian Thunder Bolts (and mercurial blaster) do wonders against those swarms of rakk that fly at you (I was also still leveling up my usage of them at the time), and take a decent chunk out of the hive as well while at it. Took me a few minutes to take down (then again, I've already beaten the game before with a hunter).
From what I've begun noticing, you won't be needing any other weapons with shock element after you've beefed up your Eridian usage, and have a weapon that guarantees an effect like the Thunder Bolt shockgun (a lightning shotgun with a decent impact, though 2-5 shots at a time before recharge, depending on parts. Carry a pair to keep suppressive fire going on anything). Have a high enough level, and the cooldown/recharge rate will actually render these weapons well worth the effort of lugging around (anywhere past level 10 prof. actually makes them rather nice to keep on hand).
I think this chart should help. Good enough skill/proficiency can make even seemingly useless weapons outright nasty to encounter (especially in the arenas). If it's not too much trouble, if anyone wants to take on Moxxi's arenas, what are your skill levels like?
PST - 3
SMG - 3
SHG - 17
RIF - 2
SNP - 5
LCH - 0
ERI - 5
PST - 16
SMG - 10
SHG - 18
RIF - 5
SNP - 11
LCH - 2
ERI - 6
Siren hasn't started any of the DLCs, nor beaten any Moxxi Arenas; and my Hunter has beaten all the 1st level arenas (5 rounds); 2nd level arenas still need to be taken care of (15 round marathons). Both characters are refined in their weapon loadouts, especially the Hunter, thanks to Knoxx's armory, and refining weapons by hunting for them. Ashamedly, I only realized the awesomeness of some Eridian weaponry by the last DLC, and I found something other than the merc blaster and cannon.