I've noticed that everyone seems to reply "shielder" to this, but in actuality, I've seen 2 hander/polearm fare much much better in 1 vs many fights.
The reason for this is that a shield slows you down incredibly. Shields also offer protection only in the front, enemy swings will often "go through" the sides of your shield if they are not directly in front of you. When you are using a shield, it often feels that the mesh is larger than the protection actually offered, with the "forcefield" effect being removed from crpg many months ago.
In my opinion, the best way to fight multilple enemies is to get a fast 2 hander or polearm (heh), and side swing like crazy. They have no penalty or "stun" for being blocked, so you can just continue to backpedal/spin/swing, and rack up kills as they hit each other trying to catch you. It's cheap and an abuse of mechanics, but hey, it works.