I don't think anyones mentioned this, but you can fight fine in the main group without a long weapon.
You've probably noticed most deaths happen due to getting ganged. You are that mobile gang. Unless you're fighting a clan with teamwork *cough us* a big clusterfuck is really just lots of mini duels. So what I tend to do is flit between them and throw in a hit, or just distract. The main worry is not to get tunnel vision on just one guy and try to kill him, cause as you've noticed, your teamates are gonna kill you instead.
Course, a long spear makes this soooo much easierXD But I do (did) this occasionally with a grosse messer.