Equip either the short blade or the sword and, when facing a large number of guards, just keep attacking them, bouncing one attack to one enemy then attacking the next. If one of the enemies tries to attack you while attacking another guard, immediately press SQUARE. This will allow you to attack while rapidly countering enemies. Another way is when the enemy dodges your attack then follows-up another attack. Do the same thing, but make sure your timing is good enough to allow you to survive even if there are six or more guards.