I have had excellent results from using a shield for parrying alongside a Porcupine, which is currently the most advanced mace weapon. Blunt weapons are a must-have in the swamp. To date, no enemy is weak to slashing damage, so swords and axes underperform. I have found spears to have an unwieldy attack swing. For mainly piercing damage, I'd rather just use a bow.

The Porcupine deals a roughly even split of blunt and piercing damage. As a result, enemies which resist one of those types are typically vulnerable to the other, meaning that the weapon does better damage overall. Frostner may outperform it against the undead, but those only figure prominently in the swamp. Once you can build a Frostner, the swamp is no longer a challenge.

As a last added bonus, the secondary (middle button) one-handed mace attack swings in an uppercut motion which has the ability to hit enemies which are located below your typical swing. This is great for attacking downhill or into shallow water.